P0C31Inverter B Cooling System Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- Hybrid or EV system warning and MIL
- Reduced drive power, especially under load or in heat
- Coolant level low in the electronics reservoir
- Likely causes
- LikelyLow coolant level or air trapped in the inverter B circuit
- PossibleWeak or failed electric coolant pump of the circuit
- RareClogged radiator or inoperative cooling fan
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.