P2227Powertrain
Powertrain · SAE
Barometric Pressure Sensor — Performance
Meaning
The barometric pressure sensor (BARO) delivers a signal within the permitted electrical range, but the value does not correspond to the data expected from engine operating conditions or other sensor readings. This is a rationality or performance fault, not a circuit fault.
Common causes
- Aged or damaged BARO sensor with calibration drift
- Blocked air inlet of the sensor (soot, moisture, insects)
- Faulty BARO sensor integrated inside the ECU (the BARO sensor is often built into the ECU/PCM)
- Abnormal pressure fluctuations in the engine bay distorting the reading
- Cross-comparison with MAP sensor detecting a discrepancy
Symptoms
- Check engine light on
- Incorrect air density calculation resulting in sub-optimal air/fuel mixture
- Performance reduction at altitude or incorrect boost map correction
- Abnormal fuel consumption
- BARO data out of range or inconsistent with current altitude in live scan tool data
Severity
Moderate: affects combustion quality and performance; rarely causes sudden failure but leads to incorrect calibrations throughout the driving session.
What to do
- Check BARO sensor live data with a scan tool and compare with expected atmospheric pressure for the current altitude
- Determine whether the sensor is integrated in the ECU or external; if external, inspect the air inlet for blockages
- Compare the BARO value with the MAP value at key-on engine-off (values should be similar)
- Replace the external BARO sensor if faulty; if internal to the ECU, replace the ECU only after ruling out all other causes
- Check for ECU software updates that may correct calibration anomalies