P0C55 code meaning
Drive Motor B Position Sensor Circuit A
Powertrain system Generic code P0Cxx codes Check engine light
What P0C55 means
P0C55 is the general circuit code for the first pickup winding (Circuit A) of the resolver on the second traction motor. It applies when the motor B controller recognises a fault on that winding but cannot assign it to a low or high level. No manufacturer documents this code publicly. GM, which runs two motors in the Volt, ELR and the two-mode trucks, files motor B winding faults under P0C57 and P0C58 instead. Compared with P0A45, which reports the motor B angle signal as a whole, P0C55 narrows the search to one winding and its two wires. CARB requires such circuit faults to be detected separately from out-of-range faults. The result is usually a warning lamp and the loss of motor B for drive or charging.
P0C55 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0C55
- Check engine lamp with hybrid system warning
- Motor B unavailable, reduced propulsion
- Engine may run more often because the second motor is offline
Common causes of P0C55
- Most likelyOpen wire or loose terminal in the motor B Circuit A lines
- PossibleDamaged or corroded motor B resolver connector
- PossibleDefective first pickup winding in the motor B resolver
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Drive motor b position sensor aWiring harnessHybrid control module
What each part of P0C55 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| C | Area: hybrid propulsion. |
| 55 | The exact fault in that area. |
What to do next
- Note P0C55 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0C55
What does P0C55 mean?
P0C55 means "Drive Motor B Position Sensor Circuit A". P0C55 is the general circuit code for the first pickup winding (Circuit A) of the resolver on the second traction motor. It is a generic code, so it means the same on every make.
Is it safe to drive with P0C55?
Drive gently and only to a workshop. With P0C55 the car can go into limp mode (reduced power) to protect itself.
Will P0C55 fail an emissions test?
Yes, it can. P0C55 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0C55 to fix?
Difficulty: hard. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P0C55 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.