P2228Powertrain
Powertrain · SAE
Barometric Pressure Sensor — Signal Low
Meaning
The barometric pressure sensor (BARO) signal is below the minimum permitted threshold. The ECU detects a voltage that is too low, indicating a short to ground, a failed sensor, or a pressure reading that is not plausible for the operating conditions.
Common causes
- Short circuit of the BARO sensor signal wire to ground
- Internally failed BARO sensor (output stuck low)
- Missing or degraded 5 V reference voltage at the sensor
- Loose or oxidised connector reducing output voltage
- Faulty ECU if BARO sensor is integrated (low reading from internal component)
Symptoms
- Check engine light on
- Barometric pressure value fixed at minimum on scan tool
- ECU calculates excessively low air density (as if vehicle were at high altitude)
- Air/fuel mixture too rich and increased fuel consumption
- Reduced performance, possible black smoke
Severity
Moderate: the low signal causes the ECU to incorrectly calculate high altitude and enrich the mixture; excess fuel can damage the catalyst and increase emissions.
What to do
- Measure BARO sensor output voltage; if below 0.5 V, investigate the short to ground
- Check 5 V reference voltage at the sensor connector
- Inspect the connector for loose or oxidised pins
- If the sensor is external, replace after ruling out wiring as the cause
- If the sensor is integrated in the ECU, consult manufacturer specifications for ECU replacement procedure