diff --git a/src/detect/ScanI2C.cpp b/src/detect/ScanI2C.cpp
index 4795d2abc17..bf01a03657d 100644
--- a/src/detect/ScanI2C.cpp
+++ b/src/detect/ScanI2C.cpp
@@ -43,7 +43,7 @@ ScanI2C::FoundDevice ScanI2C::firstAccelerometer() const
 
 ScanI2C::FoundDevice ScanI2C::firstAQI() const
 {
-    ScanI2C::DeviceType types[] = {PMSA003I, SCD4X};
+    ScanI2C::DeviceType types[] = {PMSA003I, SEN5X, SCD4X};
     return firstOfOrNONE(2, types);
 }
 
diff --git a/src/modules/Telemetry/AirQualityTelemetry.cpp b/src/modules/Telemetry/AirQualityTelemetry.cpp
index 2ccb147c39d..aac398eb9c5 100644
--- a/src/modules/Telemetry/AirQualityTelemetry.cpp
+++ b/src/modules/Telemetry/AirQualityTelemetry.cpp
@@ -22,6 +22,9 @@
 #include "Sensor/AddI2CSensorTemplate.h"
 #include "Sensor/PMSA003ISensor.h"
 #include "Sensor/SEN5XSensor.h"
+#if __has_include(<SensirionI2cScd4x.h>)
+#include "Sensor/SCD4XSensor.h"
+#endif
 
 void AirQualityTelemetryModule::i2cScanFinished(ScanI2C *i2cScanner)
 {
@@ -44,6 +47,9 @@ void AirQualityTelemetryModule::i2cScanFinished(ScanI2C *i2cScanner)
     // order by priority of metrics/values (low top, high bottom)
     addSensor<PMSA003ISensor>(i2cScanner, ScanI2C::DeviceType::PMSA003I);
     addSensor<SEN5XSensor>(i2cScanner, ScanI2C::DeviceType::SEN5X);
+#if __has_include(<SensirionI2cScd4x.h>)
+    addSensor<SCD4XSensor>(i2cScanner, ScanI2C::DeviceType::SCD4X);
+#endif
 }
 
 int32_t AirQualityTelemetryModule::runOnce()
@@ -186,7 +192,7 @@ void AirQualityTelemetryModule::drawFrame(OLEDDisplay *display, OLEDDisplayUiSta
     const auto &m = telemetry.variant.air_quality_metrics;
 
     // Check if any telemetry field has valid data
-    bool hasAny = m.has_pm10_standard || m.has_pm25_standard || m.has_pm100_standard;
+    bool hasAny = m.has_pm10_standard || m.has_pm25_standard || m.has_pm100_standard || m.has_co2;
 
     if (!hasAny) {
         display->drawString(x, currentY, "No Telemetry");
@@ -213,6 +219,8 @@ void AirQualityTelemetryModule::drawFrame(OLEDDisplay *display, OLEDDisplayUiSta
         entries.push_back("PM2.5: " + String(m.pm25_standard) + "ug/m3");
     if (m.has_pm100_standard)
         entries.push_back("PM10: " + String(m.pm100_standard) + "ug/m3");
+    if (m.has_co2)
+        entries.push_back("CO2: " + String(m.co2) + "ppm");
 
     // === Show first available metric on top-right of first line ===
     if (!entries.empty()) {
@@ -256,6 +264,9 @@ bool AirQualityTelemetryModule::handleReceivedProtobuf(const meshtastic_MeshPack
         // LOG_INFO("                  | PM1.0(Environmental)=%i, PM2.5(Environmental)=%i, PM10.0(Environmental)=%i",
         //          t->variant.air_quality_metrics.pm10_environmental, t->variant.air_quality_metrics.pm25_environmental,
         //          t->variant.air_quality_metrics.pm100_environmental);
+
+        LOG_INFO("                  | CO2=%i, CO2_T=%f, CO2_H=%f", t->variant.air_quality_metrics.co2,
+                 t->variant.air_quality_metrics.co2_temperature, t->variant.air_quality_metrics.co2_humidity);
 #endif
         // release previous packet before occupying a new spot
         if (lastMeasurementPacket != nullptr)
@@ -269,15 +280,20 @@ bool AirQualityTelemetryModule::handleReceivedProtobuf(const meshtastic_MeshPack
 
 bool AirQualityTelemetryModule::getAirQualityTelemetry(meshtastic_Telemetry *m)
 {
-    bool valid = true;
+    // Note: this is different to the case in EnvironmentTelemetryModule
+    // There, if any sensor fails to read - valid = false.
+    bool valid = false;
     bool hasSensor = false;
     m->time = getTime();
     m->which_variant = meshtastic_Telemetry_air_quality_metrics_tag;
     m->variant.air_quality_metrics = meshtastic_AirQualityMetrics_init_zero;
 
+    bool sensor_get = false;
     for (TelemetrySensor *sensor : sensors) {
         LOG_DEBUG("Reading %s", sensor->sensorName);
-        valid = valid && sensor->getMetrics(m);
+        // Note - this function doesn't get properly called if within a conditional
+        sensor_get = sensor->getMetrics(m);
+        valid = valid || sensor_get;
         hasSensor = true;
     }
 
@@ -319,12 +335,28 @@ bool AirQualityTelemetryModule::sendTelemetry(NodeNum dest, bool phoneOnly)
     m.time = getTime();
 
     if (getAirQualityTelemetry(&m)) {
-        LOG_INFO("Send: pm10_standard=%u, pm25_standard=%u, pm100_standard=%u", m.variant.air_quality_metrics.pm10_standard,
-                 m.variant.air_quality_metrics.pm25_standard, m.variant.air_quality_metrics.pm100_standard);
-        if (m.variant.air_quality_metrics.has_pm10_environmental)
-            LOG_INFO("pm10_environmental=%u, pm25_environmental=%u, pm100_environmental=%u",
-                     m.variant.air_quality_metrics.pm10_environmental, m.variant.air_quality_metrics.pm25_environmental,
-                     m.variant.air_quality_metrics.pm100_environmental);
+
+        bool hasAnyPM =
+            m.variant.air_quality_metrics.has_pm10_standard || m.variant.air_quality_metrics.has_pm25_standard ||
+            m.variant.air_quality_metrics.has_pm100_standard || m.variant.air_quality_metrics.has_pm10_environmental ||
+            m.variant.air_quality_metrics.has_pm25_environmental || m.variant.air_quality_metrics.has_pm100_environmental;
+
+        if (hasAnyPM) {
+            LOG_INFO("Send: pm10_standard=%u, pm25_standard=%u, pm100_standard=%u", m.variant.air_quality_metrics.pm10_standard,
+                     m.variant.air_quality_metrics.pm25_standard, m.variant.air_quality_metrics.pm100_standard);
+            if (m.variant.air_quality_metrics.has_pm10_environmental)
+                LOG_INFO("pm10_environmental=%u, pm25_environmental=%u, pm100_environmental=%u",
+                         m.variant.air_quality_metrics.pm10_environmental, m.variant.air_quality_metrics.pm25_environmental,
+                         m.variant.air_quality_metrics.pm100_environmental);
+        }
+
+        bool hasAnyCO2 = m.variant.air_quality_metrics.has_co2 || m.variant.air_quality_metrics.has_co2_temperature ||
+                         m.variant.air_quality_metrics.has_co2_humidity;
+
+        if (hasAnyCO2) {
+            LOG_INFO("Send: co2=%i, co2_t=%f, co2_rh=%f", m.variant.air_quality_metrics.co2,
+                     m.variant.air_quality_metrics.co2_temperature, m.variant.air_quality_metrics.co2_humidity);
+        }
 
         meshtastic_MeshPacket *p = allocDataProtobuf(m);
         p->to = dest;
diff --git a/src/modules/Telemetry/Sensor/SCD4XSensor.cpp b/src/modules/Telemetry/Sensor/SCD4XSensor.cpp
new file mode 100644
index 00000000000..4f6e28b4b26
--- /dev/null
+++ b/src/modules/Telemetry/Sensor/SCD4XSensor.cpp
@@ -0,0 +1,893 @@
+#include "configuration.h"
+
+#if !MESHTASTIC_EXCLUDE_AIR_QUALITY_SENSOR && __has_include(<SensirionI2cScd4x.h>)
+
+#include "../detect/reClockI2C.h"
+#include "../mesh/generated/meshtastic/telemetry.pb.h"
+#include "SCD4XSensor.h"
+
+#define SCD4X_NO_ERROR 0
+
+SCD4XSensor::SCD4XSensor() : TelemetrySensor(meshtastic_TelemetrySensorType_SCD4X, "SCD4X") {}
+
+bool SCD4XSensor::initDevice(TwoWire *bus, ScanI2C::FoundDevice *dev)
+{
+    LOG_INFO("Init sensor: %s", sensorName);
+
+    _bus = bus;
+    _address = dev->address.address;
+
+#ifdef SCD4X_I2C_CLOCK_SPEED
+#ifdef CAN_RECLOCK_I2C
+    uint32_t currentClock = reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, false);
+#elif !HAS_SCREEN
+    reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, true);
+#else
+    LOG_WARN("%s can't be used at this clock speed, with a screen", sensorName);
+    return false;
+#endif /* CAN_RECLOCK_I2C */
+#endif /* SCD4X_I2C_CLOCK_SPEED */
+
+    scd4x.begin(*_bus, _address);
+
+    // From SCD4X library
+    delay(30);
+
+    // Stop periodic measurement
+    if (!stopMeasurement()) {
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+        reClockI2C(currentClock, _bus, false);
+#endif
+        return false;
+    }
+
+    // Get sensor variant
+    scd4x.getSensorVariant(sensorVariant);
+
+    if (sensorVariant == SCD4X_SENSOR_VARIANT_SCD41) {
+        LOG_INFO("%s: Found SCD41", sensorName);
+        if (!powerUp()) {
+            LOG_ERROR("%s: Error trying to execute powerUp()", sensorName);
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+            reClockI2C(currentClock, _bus, false);
+#endif
+            return false;
+        }
+    }
+
+    if (!getASC(ascActive)) {
+        LOG_ERROR("%s: Unable to check if ASC is enabled", sensorName);
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+        reClockI2C(currentClock, _bus, false);
+#endif
+        return false;
+    }
+
+    // Start measurement in selected power mode (low power by default)
+    if (!startMeasurement()) {
+        LOG_ERROR("%s: Couldn't start measurement", sensorName);
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+        reClockI2C(currentClock, _bus, false);
+#endif
+        return false;
+    }
+
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+    reClockI2C(currentClock, _bus, false);
+#endif
+
+    if (state == SCD4X_MEASUREMENT) {
+        status = 1;
+    } else {
+        status = 0;
+    }
+
+    initI2CSensor();
+
+    return true;
+}
+
+bool SCD4XSensor::getMetrics(meshtastic_Telemetry *measurement)
+{
+
+    if (state != SCD4X_MEASUREMENT) {
+        LOG_ERROR("%s: Not in measurement mode", sensorName);
+        return false;
+    }
+
+    uint16_t co2, error;
+    float temperature, humidity;
+
+#ifdef SCD4X_I2C_CLOCK_SPEED
+#ifdef CAN_RECLOCK_I2C
+    uint32_t currentClock = reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, false);
+#elif !HAS_SCREEN
+    reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, true);
+#else
+    LOG_WARN("%s can't be used at this clock speed, with a screen", sensorName);
+    return false;
+#endif /* CAN_RECLOCK_I2C */
+#endif /* SCD4X_I2C_CLOCK_SPEED */
+
+    bool dataReady;
+    error = scd4x.getDataReadyStatus(dataReady);
+    if (!dataReady) {
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+        reClockI2C(currentClock, _bus, false);
+#endif
+        LOG_ERROR("SCD4X: Data is not ready");
+        return false;
+    }
+
+    error = scd4x.readMeasurement(co2, temperature, humidity);
+
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+    reClockI2C(currentClock, _bus, false);
+#endif
+
+    LOG_DEBUG("%s readings: %u ppm, %.2f degC, %.2f %rh", sensorName, co2, temperature, humidity);
+    if (error != SCD4X_NO_ERROR) {
+        LOG_DEBUG("%s: Error while getting measurements: %u", sensorName, error);
+        if (co2 == 0) {
+            LOG_ERROR("%s: Skipping invalid measurement.", sensorName);
+        }
+        return false;
+    } else {
+        measurement->variant.air_quality_metrics.has_co2_temperature = true;
+        measurement->variant.air_quality_metrics.has_co2_humidity = true;
+        measurement->variant.air_quality_metrics.has_co2 = true;
+        measurement->variant.air_quality_metrics.co2_temperature = temperature;
+        measurement->variant.air_quality_metrics.co2_humidity = humidity;
+        measurement->variant.air_quality_metrics.co2 = co2;
+        return true;
+    }
+}
+
+/**
+ * @brief Perform a forced recalibration (FRC) of the CO₂ concentration.
+ *
+ * From Sensirion SCD4X I2C Library
+ *
+ * 1. Operate the SCD4x in the operation mode later used for normal sensor
+ * operation (e.g. periodic measurement) for at least 3 minutes in an
+ * environment with a homogenous and constant CO2 concentration. The sensor
+ * must be operated at the voltage desired for the application when
+ * performing the FRC sequence. 2. Issue the stop_periodic_measurement
+ * command. 3. Issue the perform_forced_recalibration command.
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::performFRC(uint32_t targetCO2)
+{
+    uint16_t error, frcCorr;
+
+    LOG_INFO("%s: Issuing FRC. Ensure device has been working at least 3 minutes in stable target environment", sensorName);
+
+    if (!stopMeasurement()) {
+        return false;
+    }
+
+    LOG_INFO("%s: Target CO2: %u ppm", sensorName, targetCO2);
+    error = scd4x.performForcedRecalibration((uint16_t)targetCO2, frcCorr);
+
+    // SCD4X Sensirion datasheet
+    delay(400);
+
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to perform forced recalibration.", sensorName);
+        return false;
+    }
+
+    if (frcCorr == 0xFFFF) {
+        LOG_ERROR("%s: Error while performing forced recalibration.", sensorName);
+        return false;
+    }
+
+    LOG_INFO("%s: FRC Correction successful. Correction output: %u", sensorName, (uint16_t)(frcCorr - 0x8000));
+
+    return true;
+}
+
+/**
+ * @brief Start measurement mode
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::startMeasurement()
+{
+    uint16_t error;
+
+    if (state == SCD4X_MEASUREMENT) {
+        LOG_DEBUG("%s: Already in measurement mode", sensorName);
+        return true;
+    }
+
+    if (lowPower) {
+        error = scd4x.startLowPowerPeriodicMeasurement();
+    } else {
+        error = scd4x.startPeriodicMeasurement();
+    }
+
+    if (error == SCD4X_NO_ERROR) {
+        LOG_INFO("%s: Started measurement mode", sensorName);
+        if (lowPower) {
+            LOG_INFO("%s: Low power mode", sensorName);
+        } else {
+            LOG_INFO("%s: Normal power mode", sensorName);
+        }
+
+        state = SCD4X_MEASUREMENT;
+        return true;
+    } else {
+        LOG_ERROR("%s: Couldn't start measurement mode", sensorName);
+        return false;
+    }
+}
+
+/**
+ * @brief Stop measurement mode
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::stopMeasurement()
+{
+    uint16_t error;
+
+    error = scd4x.stopPeriodicMeasurement();
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to set idle mode on SCD4X.", sensorName);
+        return false;
+    }
+
+    state = SCD4X_IDLE;
+    co2MeasureStarted = 0;
+    return true;
+}
+
+/**
+ * @brief Set power mode
+ * Pass true to set low power mode
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::setPowerMode(bool _lowPower)
+{
+    lowPower = _lowPower;
+
+    if (!stopMeasurement()) {
+        return false;
+    }
+
+    if (lowPower) {
+        LOG_DEBUG("%s: Set low power mode", sensorName);
+    } else {
+        LOG_DEBUG("%s: Set normal power mode", sensorName);
+    }
+
+    return true;
+}
+
+/**
+ * @brief Check the current mode (ASC or FRC)
+ * From Sensirion SCD4X I2C Library
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::getASC(uint16_t &_ascActive)
+{
+    uint16_t error;
+    LOG_INFO("%s: Getting ASC", sensorName);
+
+    if (!stopMeasurement()) {
+        return false;
+    }
+    error = scd4x.getAutomaticSelfCalibrationEnabled(_ascActive);
+
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to send command.", sensorName);
+        return false;
+    }
+
+    if (_ascActive) {
+        LOG_INFO("%s: ASC is enabled", sensorName);
+    } else {
+        LOG_INFO("%s: FRC is enabled", sensorName);
+    }
+
+    return true;
+}
+
+/**
+ * @brief Enable or disable automatic self calibration (ASC).
+ *
+ * From Sensirion SCD4X I2C Library
+ *
+ * Sets the current state (enabled / disabled) of the ASC. By default, ASC
+ * is enabled.
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::setASC(bool ascEnabled)
+{
+    uint16_t error;
+
+    if (ascEnabled) {
+        LOG_INFO("%s: Enabling ASC", sensorName);
+    } else {
+        LOG_INFO("%s: Disabling ASC", sensorName);
+    }
+
+    if (!stopMeasurement()) {
+        return false;
+    }
+
+    error = scd4x.setAutomaticSelfCalibrationEnabled((uint16_t)ascEnabled);
+
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to send command.", sensorName);
+        return false;
+    }
+
+    error = scd4x.persistSettings();
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to make settings persistent.", sensorName);
+        return false;
+    }
+
+    if (!getASC(ascActive)) {
+        LOG_ERROR("%s: Unable to check if ASC is enabled", sensorName);
+        return false;
+    }
+
+    if (ascActive) {
+        LOG_INFO("%s: ASC is enabled", sensorName);
+    } else {
+        LOG_INFO("%s: ASC is disabled", sensorName);
+    }
+
+    return true;
+}
+
+/**
+ * @brief Set the value of ASC baseline target in ppm.
+ *
+ * From Sensirion SCD4X I2C Library.
+ *
+ * Sets the value of the ASC baseline target, i.e. the CO₂ concentration in
+ * ppm which the ASC algorithm will assume as lower-bound background to
+ * which the SCD4x is exposed to regularly within one ASC period of
+ * operation. To save the setting to the EEPROM, the persist_settings
+ * command must be issued subsequently. The factory default value is 400
+ * ppm.
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::setASCBaseline(uint32_t targetCO2)
+{
+    // TODO - Remove?
+    //  Available in library, but not described in datasheet.
+    uint16_t error;
+    LOG_INFO("%s: Setting ASC baseline to: %u", sensorName, targetCO2);
+
+    getASC(ascActive);
+    if (!ascActive) {
+        LOG_ERROR("%s: Can't set ASC baseline. ASC is not active", sensorName);
+        return false;
+    }
+
+    if (!stopMeasurement()) {
+        return false;
+    }
+
+    error = scd4x.setAutomaticSelfCalibrationTarget((uint16_t)targetCO2);
+
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to send command.", sensorName);
+        return false;
+    }
+
+    error = scd4x.persistSettings();
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to make settings persistent.", sensorName);
+        return false;
+    }
+
+    LOG_INFO("%s: Setting ASC baseline successful", sensorName);
+
+    return true;
+}
+
+/**
+ * @brief Set the temperature compensation reference.
+ *
+ * From Sensirion SCD4X I2C Library.
+ *
+ * Setting the temperature offset of the SCD4x inside the customer device
+ * allows the user to optimize the RH and T output signal.
+ * By default, the temperature offset is set to 4 °C. To save
+ * the setting to the EEPROM, the persist_settings command may be issued.
+ * Equation (1) details how the characteristic temperature offset can be
+ * calculated using the current temperature output of the sensor (TSCD4x), a
+ * reference temperature value (TReference), and the previous temperature
+ * offset (Toffset_pervious) obtained using the get_temperature_offset_raw
+ * command:
+ *
+ * Toffset_actual = TSCD4x - TReference + Toffset_pervious.
+ *
+ * Recommended temperature offset values are between 0 °C and 20 °C. The
+ * temperature offset does not impact the accuracy of the CO2 output.
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::setTemperature(float tempReference)
+{
+    uint16_t error;
+    float prevTempOffset;
+    float updatedTempOffset;
+    float tempOffset;
+    bool dataReady;
+    uint16_t co2;
+    float temperature;
+    float humidity;
+
+    LOG_INFO("%s: Setting reference temperature at: %.2f", sensorName, tempReference);
+
+    error = scd4x.getDataReadyStatus(dataReady);
+    if (!dataReady) {
+        LOG_ERROR("%s: Data is not ready", sensorName);
+        return false;
+    }
+
+    error = scd4x.readMeasurement(co2, temperature, humidity);
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to read current temperature. Error code: %u", sensorName, error);
+        return false;
+    }
+
+    LOG_INFO("%s: Current sensor temperature: %.2f", sensorName, temperature);
+
+    if (!stopMeasurement()) {
+        return false;
+    }
+
+    error = scd4x.getTemperatureOffset(prevTempOffset);
+
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to get temperature offset. Error code: %u", sensorName, error);
+        return false;
+    }
+    LOG_INFO("%s: Current sensor temperature offset: %.2f", sensorName, prevTempOffset);
+
+    tempOffset = temperature - tempReference + prevTempOffset;
+
+    LOG_INFO("%s: Setting temperature offset: %.2f", sensorName, tempOffset);
+    error = scd4x.setTemperatureOffset(tempOffset);
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to set temperature offset. Error code: %u", sensorName, error);
+        return false;
+    }
+
+    error = scd4x.persistSettings();
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to make settings persistent. Error code: %u", sensorName, error);
+        return false;
+    }
+
+    scd4x.getTemperatureOffset(updatedTempOffset);
+    LOG_INFO("%s: Updated sensor temperature offset: %.2f", sensorName, updatedTempOffset);
+
+    return true;
+}
+
+/**
+ * @brief Get the sensor altitude.
+ *
+ * From Sensirion SCD4X I2C Library.
+ *
+ * Altitude in meters above sea level can be set after device installation.
+ * Valid value between 0 and 3000m. This overrides pressure offset.
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::getAltitude(uint16_t &altitude)
+{
+    uint16_t error;
+    LOG_INFO("%s: Requesting sensor altitude", sensorName);
+
+    if (!stopMeasurement()) {
+        return false;
+    }
+
+    error = scd4x.getSensorAltitude(altitude);
+
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to get altitude. Error code: %u", sensorName, error);
+        return false;
+    }
+    LOG_INFO("%s: Sensor altitude: %u", sensorName, altitude);
+
+    return true;
+}
+
+/**
+ * @brief Get the ambient pressure around the sensor.
+ *
+ * From Sensirion SCD4X I2C Library.
+ *
+ * Gets the ambient pressure in Pa.
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::getAmbientPressure(uint32_t &ambientPressure)
+{
+    uint16_t error;
+    LOG_INFO("%s: Requesting sensor ambient pressure", sensorName);
+
+    error = scd4x.getAmbientPressure(ambientPressure);
+
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to get altitude. Error code: %u", sensorName, error);
+        return false;
+    }
+    LOG_INFO("%s: Sensor ambient pressure: %u", sensorName, ambientPressure);
+
+    return true;
+}
+
+/**
+ * @brief Set the sensor altitude.
+ *
+ * From Sensirion SCD4X I2C Library.
+ *
+ * Altitude in meters above sea level can be set after device installation.
+ * Valid value between 0 and 3000m. This overrides pressure offset.
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::setAltitude(uint32_t altitude)
+{
+    uint16_t error;
+
+    if (!stopMeasurement()) {
+        return false;
+    }
+
+    error = scd4x.setSensorAltitude(altitude);
+
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to set altitude. Error code: %u", sensorName, error);
+        return false;
+    }
+
+    error = scd4x.persistSettings();
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to make settings persistent. Error code: %u", sensorName, error);
+        return false;
+    }
+
+    return true;
+}
+
+/**
+ * @brief Set the ambient pressure around the sensor.
+ *
+ * From Sensirion SCD4X I2C Library.
+ *
+ * The set_ambient_pressure command can be sent during periodic measurements
+ * to enable continuous pressure compensation. Note that setting an ambient
+ * pressure overrides any pressure compensation based on a previously set
+ * sensor altitude. Use of this command is highly recommended for
+ * applications experiencing significant ambient pressure changes to ensure
+ * sensor accuracy. Valid input values are between 70000 - 120000 Pa. The
+ * default value is 101300 Pa.
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::setAmbientPressure(uint32_t ambientPressure)
+{
+    uint16_t error;
+
+    error = scd4x.setAmbientPressure(ambientPressure);
+
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to set altitude. Error code: %u", sensorName, error);
+        return false;
+    }
+
+    // Sensirion doesn't indicate if this is necessary. We send it anyway
+    error = scd4x.persistSettings();
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to make settings persistent. Error code: %u", sensorName, error);
+        return false;
+    }
+
+    return true;
+}
+
+/**
+ * @brief Perform factory reset to erase the settings stored in the EEPROM.
+ *
+ * From Sensirion SCD4X I2C Library.
+ *
+ * The perform_factory_reset command resets all configuration settings
+ * stored in the EEPROM and erases the FRC and ASC algorithm history.
+ * @note This function should not change the clock
+ */
+bool SCD4XSensor::factoryReset()
+{
+    uint16_t error;
+
+    LOG_INFO("%s: Requesting factory reset", sensorName);
+
+    if (!stopMeasurement()) {
+        return false;
+    }
+
+    error = scd4x.performFactoryReset();
+
+    if (error != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Unable to do factory reset. Error code: %u", sensorName, error);
+        return false;
+    }
+
+    LOG_INFO("%s: Factory reset successful", sensorName);
+
+    return true;
+}
+
+/**
+ * @brief Put the sensor into sleep mode from idle mode.
+ *
+ * From Sensirion SCD4X I2C Library.
+ *
+ * Put the sensor from idle to sleep to reduce power consumption. Can be
+ * used to power down when operating the sensor in power-cycled single shot
+ * mode.
+ * @note This command is only available in idle mode. Only for SCD41.
+ */
+bool SCD4XSensor::powerDown()
+{
+    LOG_INFO("%s: Trying to send sensor to sleep", sensorName);
+
+    if (sensorVariant != SCD4X_SENSOR_VARIANT_SCD41) {
+        LOG_WARN("SCD4X: Can't send sensor to sleep. Incorrect variant. Ignoring");
+        return true;
+    }
+
+#ifdef SCD4X_I2C_CLOCK_SPEED
+#ifdef CAN_RECLOCK_I2C
+    uint32_t currentClock = reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, false);
+#elif !HAS_SCREEN
+    reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, true);
+#else
+    LOG_WARN("%s can't be used at this clock speed, with a screen", sensorName);
+    return false;
+#endif /* CAN_RECLOCK_I2C */
+#endif /* SCD4X_I2C_CLOCK_SPEED */
+
+    if (!stopMeasurement()) {
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+        reClockI2C(currentClock, _bus, false);
+#endif
+        return false;
+    }
+
+    if (scd4x.powerDown() != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Error trying to execute sleep()", sensorName);
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+        reClockI2C(currentClock, _bus, false);
+#endif
+        return false;
+    }
+
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+    reClockI2C(currentClock, _bus, false);
+#endif
+
+    state = SCD4X_OFF;
+    return true;
+}
+
+/**
+ * @brief Wake up sensor from sleep mode to idle mode (powerUp)
+ *
+ * From Sensirion SCD4X I2C Library.
+ *
+ * Wake up the sensor from sleep mode into idle mode. Note that the SCD4x
+ * does not acknowledge the wake_up command. The sensor's idle state after
+ * wake up can be verified by reading out the serial number.
+ * @note This command is only available for SCD41.
+ * @note This function can't change clock (used in init)
+ */
+bool SCD4XSensor::powerUp()
+{
+    LOG_INFO("%s: Waking up", sensorName);
+
+    if (scd4x.wakeUp() != SCD4X_NO_ERROR) {
+        LOG_ERROR("%s: Error trying to execute wakeUp()", sensorName);
+        return false;
+    }
+
+    state = SCD4X_IDLE;
+
+    return true;
+}
+
+/**
+ * @brief Check if sensor is in measurement mode
+ */
+bool SCD4XSensor::isActive()
+{
+    return state == SCD4X_MEASUREMENT;
+}
+
+/**
+ * @brief Start measurement mode
+ * @note Not used in admin comands, getMetrics or init, can change clock.
+ */
+uint32_t SCD4XSensor::wakeUp()
+{
+
+#ifdef SCD4X_I2C_CLOCK_SPEED
+#ifdef CAN_RECLOCK_I2C
+    uint32_t currentClock = reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, false);
+#elif !HAS_SCREEN
+    reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, true);
+#else
+    LOG_WARN("%s can't be used at this clock speed, with a screen", sensorName);
+    return 0;
+#endif /* CAN_RECLOCK_I2C */
+#endif /* SCD4X_I2C_CLOCK_SPEED */
+
+    if (startMeasurement()) {
+        co2MeasureStarted = getTime();
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+        reClockI2C(currentClock, _bus, false);
+#endif
+        return SCD4X_WARMUP_MS;
+    }
+
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+    reClockI2C(currentClock, _bus, false);
+#endif
+
+    return 0;
+}
+
+/**
+ * @brief Stop measurement mode
+ * @note Not used in admin comands, getMetrics or init, can change clock.
+ */
+void SCD4XSensor::sleep()
+{
+#ifdef SCD4X_I2C_CLOCK_SPEED
+#ifdef CAN_RECLOCK_I2C
+    uint32_t currentClock = reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, false);
+#elif !HAS_SCREEN
+    reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, true);
+#else
+    LOG_WARN("%s can't be used at this clock speed, with a screen", sensorName);
+    return;
+#endif /* CAN_RECLOCK_I2C */
+#endif /* SCD4X_I2C_CLOCK_SPEED */
+
+    stopMeasurement();
+
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+    reClockI2C(currentClock, _bus, false);
+#endif
+}
+
+/**
+ * @brief Can sleep function
+ *
+ * Power consumption is very low on lowPower mode, modify this function if
+ * you still want to override this behaviour. Otherwise, sleep is disabled
+ * routinely in low power mode
+ */
+bool SCD4XSensor::canSleep()
+{
+    return lowPower ? false : true;
+}
+
+int32_t SCD4XSensor::wakeUpTimeMs()
+{
+    return SCD4X_WARMUP_MS;
+}
+
+int32_t SCD4XSensor::pendingForReadyMs()
+{
+    uint32_t now;
+    now = getTime();
+    uint32_t sinceCO2MeasureStarted = (now - co2MeasureStarted) * 1000;
+    LOG_DEBUG("%s: Since measure started: %ums", sensorName, sinceCO2MeasureStarted);
+
+    if (sinceCO2MeasureStarted < SCD4X_WARMUP_MS) {
+        LOG_INFO("%s: not enough time passed since starting measurement", sensorName);
+        return SCD4X_WARMUP_MS - sinceCO2MeasureStarted;
+    }
+    return 0;
+}
+
+AdminMessageHandleResult SCD4XSensor::handleAdminMessage(const meshtastic_MeshPacket &mp, meshtastic_AdminMessage *request,
+                                                         meshtastic_AdminMessage *response)
+{
+    AdminMessageHandleResult result;
+
+#ifdef SCD4X_I2C_CLOCK_SPEED
+#ifdef CAN_RECLOCK_I2C
+    uint32_t currentClock = reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, false);
+#elif !HAS_SCREEN
+    reClockI2C(SCD4X_I2C_CLOCK_SPEED, _bus, true);
+#else
+    LOG_WARN("%s can't be used at this clock speed, with a screen", sensorName);
+    return AdminMessageHandleResult::NOT_HANDLED;
+#endif /* CAN_RECLOCK_I2C */
+#endif /* SCD4X_I2C_CLOCK_SPEED */
+
+    // TODO: potentially add selftest command?
+    switch (request->which_payload_variant) {
+    case meshtastic_AdminMessage_sensor_config_tag:
+        // Check for ASC-FRC request first
+        if (!request->sensor_config.has_scd4x_config) {
+            result = AdminMessageHandleResult::NOT_HANDLED;
+            break;
+        }
+
+        if (request->sensor_config.scd4x_config.has_factory_reset) {
+            LOG_DEBUG("%s: Requested factory reset", sensorName);
+            this->factoryReset();
+        } else {
+
+            if (request->sensor_config.scd4x_config.has_set_asc) {
+                this->setASC(request->sensor_config.scd4x_config.set_asc);
+                if (request->sensor_config.scd4x_config.set_asc == false) {
+                    LOG_DEBUG("%s: Request for FRC", sensorName);
+                    if (request->sensor_config.scd4x_config.has_set_target_co2_conc) {
+                        this->performFRC(request->sensor_config.scd4x_config.set_target_co2_conc);
+                    } else {
+                        // FRC requested but no target CO2 provided
+                        LOG_ERROR("%s: target CO2 not provided", sensorName);
+                        result = AdminMessageHandleResult::NOT_HANDLED;
+                        break;
+                    }
+                } else {
+                    LOG_DEBUG("%s: Request for ASC", sensorName);
+                    if (request->sensor_config.scd4x_config.has_set_target_co2_conc) {
+                        LOG_DEBUG("%s: Request has target CO2", sensorName);
+                        // TODO - Remove? see setASCBaseline function
+                        this->setASCBaseline(request->sensor_config.scd4x_config.set_target_co2_conc);
+                    } else {
+                        LOG_DEBUG("%s: Request doesn't have target CO2", sensorName);
+                    }
+                }
+            }
+
+            // Check for temperature offset
+            // NOTE: this requires to have a sensor working on stable environment
+            // And to make it between readings
+            if (request->sensor_config.scd4x_config.has_set_temperature) {
+                this->setTemperature(request->sensor_config.scd4x_config.set_temperature);
+            }
+
+            // Check for altitude or pressure offset
+            if (request->sensor_config.scd4x_config.has_set_altitude) {
+                this->setAltitude(request->sensor_config.scd4x_config.set_altitude);
+            } else if (request->sensor_config.scd4x_config.has_set_ambient_pressure) {
+                this->setAmbientPressure(request->sensor_config.scd4x_config.set_ambient_pressure);
+            }
+
+            // Check for low power mode
+            // NOTE: to switch from one mode to another do:
+            // setPowerMode -> startMeasurement
+            if (request->sensor_config.scd4x_config.has_set_power_mode) {
+                this->setPowerMode(request->sensor_config.scd4x_config.set_power_mode);
+            }
+        }
+
+        // Start measurement mode
+        this->startMeasurement();
+
+        result = AdminMessageHandleResult::HANDLED;
+        break;
+
+    default:
+        result = AdminMessageHandleResult::NOT_HANDLED;
+    }
+
+#if defined(SCD4X_I2C_CLOCK_SPEED) && defined(CAN_RECLOCK_I2C)
+    reClockI2C(currentClock, _bus, false);
+#endif
+
+    return result;
+}
+
+#endif
\ No newline at end of file
diff --git a/src/modules/Telemetry/Sensor/SCD4XSensor.h b/src/modules/Telemetry/Sensor/SCD4XSensor.h
new file mode 100644
index 00000000000..1ed86a183b9
--- /dev/null
+++ b/src/modules/Telemetry/Sensor/SCD4XSensor.h
@@ -0,0 +1,63 @@
+#include "configuration.h"
+
+#if !MESHTASTIC_EXCLUDE_AIR_QUALITY_SENSOR && __has_include(<SensirionI2cScd4x.h>)
+
+#include "../mesh/generated/meshtastic/telemetry.pb.h"
+#include "RTC.h"
+#include "TelemetrySensor.h"
+#include <SensirionI2cScd4x.h>
+
+// Max speed 400kHz
+#define SCD4X_I2C_CLOCK_SPEED 100000
+#define SCD4X_WARMUP_MS 5000
+
+class SCD4XSensor : public TelemetrySensor
+{
+  private:
+    SensirionI2cScd4x scd4x;
+    TwoWire *_bus{};
+    uint8_t _address{};
+
+    bool performFRC(uint32_t targetCO2);
+    bool setASCBaseline(uint32_t targetCO2);
+    bool getASC(uint16_t &ascEnabled);
+    bool setASC(bool ascEnabled);
+    bool setTemperature(float tempReference);
+    bool getAltitude(uint16_t &altitude);
+    bool setAltitude(uint32_t altitude);
+    bool getAmbientPressure(uint32_t &ambientPressure);
+    bool setAmbientPressure(uint32_t ambientPressure);
+    bool factoryReset();
+    bool setPowerMode(bool _lowPower);
+    bool startMeasurement();
+    bool stopMeasurement();
+
+    uint16_t ascActive = 1;
+    // low power measurement mode (on sensirion side). Disables sleep mode
+    // Improvement and testing needed for timings
+    bool lowPower = true;
+    uint32_t co2MeasureStarted = 0;
+
+  public:
+    SCD4XSensor();
+    virtual bool getMetrics(meshtastic_Telemetry *measurement) override;
+    virtual bool initDevice(TwoWire *bus, ScanI2C::FoundDevice *dev) override;
+
+    enum SCD4XState { SCD4X_OFF, SCD4X_IDLE, SCD4X_MEASUREMENT };
+    SCD4XState state = SCD4X_OFF;
+    SCD4xSensorVariant sensorVariant{};
+
+    virtual bool isActive() override;
+
+    virtual void sleep() override;      // Stops measurement (measurement -> idle)
+    virtual uint32_t wakeUp() override; // Starts measurement (idle -> measurement)
+    bool powerDown();                   // Powers down sensor (idle -> power-off)
+    bool powerUp();                     // Powers the sensor (power-off -> idle)
+    virtual bool canSleep() override;
+    virtual int32_t wakeUpTimeMs() override;
+    virtual int32_t pendingForReadyMs() override;
+    AdminMessageHandleResult handleAdminMessage(const meshtastic_MeshPacket &mp, meshtastic_AdminMessage *request,
+                                                meshtastic_AdminMessage *response) override;
+};
+
+#endif
\ No newline at end of file
diff --git a/src/serialization/MeshPacketSerializer.cpp b/src/serialization/MeshPacketSerializer.cpp
index 92e70036811..042bc376396 100644
--- a/src/serialization/MeshPacketSerializer.cpp
+++ b/src/serialization/MeshPacketSerializer.cpp
@@ -149,18 +149,15 @@ std::string MeshPacketSerializer::JsonSerialize(const meshtastic_MeshPacket *mp,
                     if (decoded->variant.air_quality_metrics.has_pm100_standard) {
                         msgPayload["pm100"] = new JSONValue((unsigned int)decoded->variant.air_quality_metrics.pm100_standard);
                     }
-                    // if (decoded->variant.air_quality_metrics.has_pm10_environmental) {
-                    //     msgPayload["pm10_e"] =
-                    //         new JSONValue((unsigned int)decoded->variant.air_quality_metrics.pm10_environmental);
-                    // }
-                    // if (decoded->variant.air_quality_metrics.has_pm25_environmental) {
-                    //     msgPayload["pm25_e"] =
-                    //         new JSONValue((unsigned int)decoded->variant.air_quality_metrics.pm25_environmental);
-                    // }
-                    // if (decoded->variant.air_quality_metrics.has_pm100_environmental) {
-                    //     msgPayload["pm100_e"] =
-                    //         new JSONValue((unsigned int)decoded->variant.air_quality_metrics.pm100_environmental);
-                    // }
+                    if (decoded->variant.air_quality_metrics.has_co2) {
+                        msgPayload["co2"] = new JSONValue((unsigned int)decoded->variant.air_quality_metrics.co2);
+                    }
+                    if (decoded->variant.air_quality_metrics.has_co2_temperature) {
+                        msgPayload["co2_temperature"] = new JSONValue(decoded->variant.air_quality_metrics.co2_temperature);
+                    }
+                    if (decoded->variant.air_quality_metrics.has_co2_humidity) {
+                        msgPayload["co2_humidity"] = new JSONValue(decoded->variant.air_quality_metrics.co2_humidity);
+                    }
                 } else if (decoded->which_variant == meshtastic_Telemetry_power_metrics_tag) {
                     if (decoded->variant.power_metrics.has_ch1_voltage) {
                         msgPayload["voltage_ch1"] = new JSONValue(decoded->variant.power_metrics.ch1_voltage);
diff --git a/src/serialization/MeshPacketSerializer_nRF52.cpp b/src/serialization/MeshPacketSerializer_nRF52.cpp
index 80aef0e9477..a0ad4e4b9d7 100644
--- a/src/serialization/MeshPacketSerializer_nRF52.cpp
+++ b/src/serialization/MeshPacketSerializer_nRF52.cpp
@@ -120,15 +120,15 @@ std::string MeshPacketSerializer::JsonSerialize(const meshtastic_MeshPacket *mp,
                     if (decoded->variant.air_quality_metrics.has_pm100_standard) {
                         jsonObj["payload"]["pm100"] = (unsigned int)decoded->variant.air_quality_metrics.pm100_standard;
                     }
-                    // if (decoded->variant.air_quality_metrics.has_pm10_environmental) {
-                    //     jsonObj["payload"]["pm10_e"] = (unsigned int)decoded->variant.air_quality_metrics.pm10_environmental;
-                    // }
-                    // if (decoded->variant.air_quality_metrics.has_pm25_environmental) {
-                    //     jsonObj["payload"]["pm25_e"] = (unsigned int)decoded->variant.air_quality_metrics.pm25_environmental;
-                    // }
-                    // if (decoded->variant.air_quality_metrics.has_pm100_environmental) {
-                    //     jsonObj["payload"]["pm100_e"] = (unsigned int)decoded->variant.air_quality_metrics.pm100_environmental;
-                    // }
+                    if (decoded->variant.air_quality_metrics.has_co2) {
+                        jsonObj["payload"]["co2"] = (unsigned int)decoded->variant.air_quality_metrics.co2;
+                    }
+                    if (decoded->variant.air_quality_metrics.has_co2_temperature) {
+                        jsonObj["payload"]["co2_temperature"] = decoded->variant.air_quality_metrics.co2_temperature;
+                    }
+                    if (decoded->variant.air_quality_metrics.has_co2_humidity) {
+                        jsonObj["payload"]["co2_humidity"] = decoded->variant.air_quality_metrics.co2_humidity;
+                    }
                 } else if (decoded->which_variant == meshtastic_Telemetry_power_metrics_tag) {
                     if (decoded->variant.power_metrics.has_ch1_voltage) {
                         jsonObj["payload"]["voltage_ch1"] = decoded->variant.power_metrics.ch1_voltage;