P2CBAFan 2 Overspeed
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- With P2CBA the controller finds fan 2 spinning clearly faster than its own estimate of what the current command should produce. GM documents the check in tables 23OBDG07 and 24OBDG07: the reported speed minus the estimated speed must exceed a margin of 1400 to 4050 rpm, depending on the operating point, for 20 s with more than 9.5 V on board, and the lamp follows on the second trip. A separate GM code covers readings beyond 4999 rpm that cannot be real, so P2CBA points to a fan that really turns too fast or a motor controller that ignores its command. Typical reasons are a broken or missing blade section, a damaged shroud letting the rotor run free, or a fan module that drives at full power. GM's 2025 diesel table does not use P2CBA. Underspeed of the same fan is P2CB9, fan 1 overspeed P0495.
- What you may notice
- Check engine light after two trips
- Unusually loud or vibrating fan noise
- Fan runs at high speed even with a cool engine
- Likely causes
- LikelyFan blade broken or partly missing, less load on the motor
- PossibleFan electronics drive the motor harder than commanded
- PossibleImplausible speed feedback from the fan module
- RareShroud damaged or detached so the rotor runs free
- 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: €80 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.