P0C08 code meaning
Drive Motor B Phase U-V-W Circuit/Open
Powertrain system Generic code P0Cxx codes Check engine light
What P0C08 means
P0C08 is the open-phase check for drive motor B, the motor B twin of P0C05. GM runs it on the 2011 Volt and the 2012 two-mode trucks: each phase is checked as the rotor passes its axis, and a phase axis current below 9 A while at least 23 A is commanded, with the rotor within 30 degrees and over 35 V on the inverter, counts as a miss. Around 200 failed samples set it, Type A, one trip. Later GM tables up to 2016 keep the same logic. GM's eAssist has only one machine and no P0C08. The usual causes are a loose three-phase terminal, an open stator winding or an inverter stage that does not conduct. Motor B then delivers no torque, the MIL lights and drive power is reduced.
P0C08 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.5 to 8 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0C08
- Malfunction indicator lamp after one drive
- Reduced propulsion power
- Engine running more often than usual
Common causes of P0C08
- Most likelyLoose or open three-phase terminal between inverter and motor B
- PossibleOpen stator winding in drive motor B
- PossibleInverter stage for motor B not conducting
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Drive motor b phase uvwDrive motor b inverter
What each part of P0C08 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. |
| 08 | The exact fault in that area. |
What to do next
- Note P0C08 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 P0C08
What does P0C08 mean?
P0C08 means "Drive Motor B Phase U-V-W Circuit/Open". P0C08 is the open-phase check for drive motor B, the motor B twin of P0C05. It is a generic code, so it means the same on every make.
Is it safe to drive with P0C08?
Drive gently and only to a workshop. With P0C08 the car can go into limp mode (reduced power) to protect itself.
Will P0C08 fail an emissions test?
Yes, it can. P0C08 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 P0C08 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 8 hours of work. This is a job for a workshop.
Will P0C08 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.