P0C31 code meaning
Inverter B Cooling System Performance
Powertrain system Generic code P0Cxx codes Check engine light
What P0C31 means
P0C31 reports that the cooling circuit of a second power inverter does not remove heat as expected; inverter A has its own code, P0A93. Vehicles with two separately cooled power electronics units, for example a front and a rear drive unit, need this second code. CARB requires hybrid OBD to monitor the parts used for inverter thermal management and, where feasible, to check the cooling performance itself. No manufacturer documents P0C31 publicly. For the analogous P0A93, Hyundai's 2011 Sonata Hybrid bulletin 14-HC-001 points to the electric water pump, and coolant pump faults of the B circuit are reported as P0B38 or P0C74. To protect the semiconductors the controller limits motor power. A low coolant level or trapped air is worth checking first.
P0C31 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0C31
- Hybrid or EV system warning and MIL
- Reduced drive power, especially under load or in heat
- Coolant level low in the electronics reservoir
Common causes of P0C31
- Most likelyLow coolant level or air trapped in the inverter B circuit
- PossibleWeak or failed electric coolant pump of the circuit
- Less likelyClogged radiator or inoperative cooling fan
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Inverter bInverter b cooling
What each part of P0C31 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. |
| 31 | The exact fault in that area. |
What to do next
- Note P0C31 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 P0C31
What does P0C31 mean?
P0C31 means "Inverter B Cooling System Performance". P0C31 reports that the cooling circuit of a second power inverter does not remove heat as expected; inverter A has its own code, P0A93. It is a generic code, so it means the same on every make.
Is it safe to drive with P0C31?
Drive gently and only to a workshop. With P0C31 the car can go into limp mode (reduced power) to protect itself.
Will P0C31 fail an emissions test?
Yes, it can. P0C31 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 P0C31 to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will P0C31 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.