P0C57Drive Motor B Position Sensor Circuit A Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0C57 means the reference level on Circuit A of the motor B resolver, the S1/S3 winding in GM wiring, has sunk below its limit. GM checks it exactly like the motor A line: under 0.5 V on the 2011 and 2016 Volt and the 2012 two-mode trucks, under 0.10 V on the 2019 Volt, with Type A on the early cars and Type B from 2016. In the field it rarely stands alone. GM preliminary information PIC5856A to F for 2011-13 Volt and 2014-16 ELR groups P0C57 with P0C58 and P0C62: if wiring checks and normal diagnosis find nothing, the motor B position sensor is replaced and the drive motor generator control module is brought to its latest calibration. A genuine harness fault to ground still has to be excluded before any parts are ordered.
- What you may notice
- Service engine soon lamp, current or in history
- Often stored together with P0C58 and P0C62
- Reduced propulsion
- Likely causes
- LikelyFaulty motor B position sensor (resolver stator) on Volt and ELR (GM PIC5856)
- PossibleCircuit A line of motor B shorted to ground in the harness
- RareDrive motor generator control module not on the latest calibration
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.