P2DCCStarter/Generator Position Sensor Correlation
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2DCC reports that the rotor position or speed the starter/generator derives from its own sensor disagrees with an independent reference. For a belt-driven machine the natural reference is the crankshaft: engine speed times the pulley ratio has to match machine speed. GM's eAssist runs this comparison under the drive motor performance code P0A90: more than 1,000 rpm between machine and ECM speed for 1.5 s within 2 s sets it as a one-trip Type A, while gaps above 500 rpm are counted over two key cycles. GM also watches the resolver for a tracking error above 5 degrees. A slipping belt can therefore look like a sensor fault. No manufacturer documents P2DCC publicly. Lacking a reliable angle, the controller usually stops assist and auto-start; CARB asks that such generator faults be detected.
- What you may notice
- Start-stop and electric assist disabled
- Belt squeal or engine restart via 12 V starter instead
- Check engine light
- Likely causes
- LikelySlipping drive belt or weak belt tensioner
- PossibleRotor position sensor degraded or shifted
- RareFaulty engine speed reference from the crankshaft sensor or its CAN signal
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €2,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.