What Does P0C31 Mean?
DTC P0C31 indicates the cooling system for inverter B is not performing within its expected parameters. The inverter converts DC battery power to AC for the electric motor, generating substantial heat in the process. If the cooling system cannot maintain proper temperatures, the inverter will derate or shut down to protect its power electronics from thermal damage.
Safety Warning
Insufficient inverter cooling can cause the power electronics to overheat, leading to power derating, limp mode, or complete shutdown of the electric drive system. In extreme thermal events, inverter component failure could occur. Do not drive aggressively until repaired.
Common Causes
25%
Low coolant level in the inverter cooling circuit
25%
Failed or degraded electric coolant pump for the inverter circuit
20%
Blocked or restricted coolant passages in the inverter heat exchanger
15%
Air trapped in the inverter cooling loop preventing proper circulation
15%
Faulty inverter coolant temperature sensor giving false readings
Diagnostic Steps
1
Check the inverter cooling system coolant level and condition — top off if low and inspect for leaks.
2
Monitor inverter B temperature on a scan tool during operation to confirm the cooling performance issue.
3
Verify the electric coolant pump for the inverter circuit is running by listening for operation or checking current draw.
4
Inspect the inverter heat exchanger and coolant lines for blockages, kinks, or collapsed hoses.
5
Bleed any air from the inverter cooling circuit following the manufacturer's procedure, as air pockets significantly reduce cooling efficiency.
6
If coolant flow is confirmed adequate, test or replace the inverter coolant temperature sensor.
Estimated Repair Cost
$200 - $1,500
Parts + labor, varies by vehicle and location
DTC P0C31 indicates the cooling system for inverter B is not performing within its expected parameters. The inverter converts DC battery power to AC for the electric motor, generating substantial heat in the process. If the cooling system cannot maintain proper temperatures, the inverter will derate...
The most common cause of P0C31 (Inverter "B" Cooling System Performance) is: Low coolant level in the inverter cooling circuit
Typical repair costs for P0C31 range from $200 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Insufficient inverter cooling can cause the power electronics to overheat, leading to power derating, limp mode, or complete shutdown of the electric drive system. In extreme thermal events, inverter component failure could occur. Do not drive aggressively until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0C31 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Hybrid/EV Inverter Cooling
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
