Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the part of the car that helps cool down the electric motor isn't working as well as it should. Imagine if your fan at home stopped blowing air, it would get hot quickly. The car's cooling system is like that fan.
The P0C31 code is triggered when the vehicle's control module detects that the cooling system for the inverter B is not performing within the expected parameters.
The inverter converts the DC power from the battery into AC power for the electric motor. Inverter B refers to a specific part of this system. The cooling system is crucial to prevent overheating and ensure efficient operation. If the cooling system is underperforming, it can lead to overheating and potential damage to the inverter.
• Check engine light is on
• Reduced power from the electric motor
• Overheating warning light
• Low coolant level
• Faulty cooling fan
• Blocked coolant passages
Inverter: A device that converts DC power from the battery to AC power for the electric motor.
Coolant: A fluid used to remove excess heat from the engine or other components.
• Check coolant level and top up if necessary
• Inspect cooling fan operation
• Check for blockages in the coolant passages
• Refill coolant to the appropriate level
• Replace or repair the cooling fan
• Clean or flush the coolant passages
• Coolant refill tool
• Multimeter
• Cooling system pressure tester
$150 - $500
Moderate
• Toyota Prius
• Chevrolet Volt
• Nissan Leaf
• Regularly check and maintain coolant levels
• Inspect cooling system components during routine maintenance
• Ensure the cooling fan is functioning properly
Cooling System Performance
• Do not ignore the check engine light
• Avoid driving the vehicle excessively until the issue is resolved
Cooling system components may be covered under the vehicle's powertrain warranty.
This code has been more common in hybrid and electric vehicles as they rely heavily on efficient cooling systems.
Moderate – Addressing this issue promptly can prevent further damage to the inverter.
Ignoring this code can lead to overheating, which may cause further damage and potentially unsafe driving conditions.
• Vehicle at operating temperature
• Engine running
The inverter is typically located near the electric motor, often under the hood of the vehicle.
Q: Can I drive with a P0C31 code?
A: It's not recommended to drive for long distances with this code as it may lead to overheating and further damage.
Q: How often should I check the coolant level?
A: It's a good practice to check the coolant level at least once a month or during regular maintenance checks.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
View on Amazon
Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.