P227ABarometric Pressure Sensor C Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P227A is the general circuit fault of barometric pressure sensor C, used when the control unit finds the signal missing or unusable without classifying it as too low or too high. Sensor C is not necessarily a separate ambient sensor: in GM's 2018 diesel tables the BARO C channel belongs to the turbocharger inlet pressure sensor, GM also uses it on the supercharged 6.2 L LT4, and on its 2023-2024 twin-throttle engine it reads pressure ahead of a throttle. No manufacturer documents P227A itself publicly; GM divides circuit monitoring of sensor C into P227C (low), P227D (high) and P227E (erratic). The matching general codes for sensors A and B are P2226 and P222A. With a substitute value the engine keeps running, but altitude and boost corrections lose accuracy.
- What you may notice
- MIL on
- Usually no noticeable change in driving; slight power loss at altitude possible
- Likely causes
- LikelyLoose connector, corroded pins or damaged wiring at sensor C
- PossibleSensor C itself failed
- Rare5 V reference or sensor ground shared with other sensors disturbed
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €40 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.