P0C0B code meaning
Drive Motor A Inverter Power Supply Circuit/Open
Powertrain system Generic code P0Cxx codes Check engine light
What P0C0B means
P0C0B flags a lost or interrupted supply inside the motor A inverter. GM reads it from the IGBT module status: when the gate drive supply falls below its threshold, the module reports a bias fault; on eAssist the 5 V rail below 3.5 to 4.3 V or the 15 V rail below 10.4 to 12.6 V counts, with run/crank above 7 V. The 2012 trucks enable it between 9.5 and 18 V; the 2016 to 2019 tables need 0.002 to 0.168 s of fault within short windows, Type A, one trip. Mercedes applies the code to the high-voltage supply of the inverter in the belt starter-alternator of P3 hybrids (subtypes 16 and 17) and replaces that unit. Expect loss of electric drive or engine start.
P0C0B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.5 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0C0B
- Malfunction indicator lamp after one drive
- Electric drive or motor generator unavailable
- Engine cannot be started, only electric driving possible (Mercedes P3 hybrids)
Common causes of P0C0B
- Most likelyFailed gate-drive power supply inside the motor A inverter
- PossibleLow 12 V feed, blown fuse or poor ground to the inverter control board
- Less likelyOpen high-voltage feed to the inverter, e.g. in a belt starter-alternator (Mercedes LI15.40-P-077947)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Drive motor a inverterWiring harnessHybrid control module
What each part of P0C0B 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. |
| 0B | The exact fault in that area. |
What to do next
- Note P0C0B 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 P0C0B
What does P0C0B mean?
P0C0B means "Drive Motor A Inverter Power Supply Circuit/Open". P0C0B flags a lost or interrupted supply inside the motor A inverter. It is a generic code, so it means the same on every make.
Is it safe to drive with P0C0B?
Drive gently and only to a workshop. With P0C0B the car can go into limp mode (reduced power) to protect itself.
Will P0C0B fail an emissions test?
Yes, it can. P0C0B 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 P0C0B to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 6 hours of work. This is a job for a workshop.
Will P0C0B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.