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 car's computer thinks the part that controls the battery's cooling system is getting too hot or using too much power.
The vehicle's control system has detected that the current or temperature in the control circuit for the coolant control valve is too high.
The P0E21 code indicates an issue with the control circuit for the Hybrid/EV battery pack coolant control valve B. This can be due to excessive current draw or high temperature, suggesting a potential fault in the valve or its control circuitry.
• Check engine light is on
• Reduced battery cooling efficiency
• Potential overheating of the battery
• Faulty coolant control valve B
• Wiring issues in the control circuit
• Malfunctioning control module
Coolant Control Valve: A device that regulates the flow of coolant to the battery pack.
Control Circuit: The electrical pathway that controls a component's operation.
• Perform a visual inspection of the coolant control valve and wiring.
• Check for any blown fuses related to the control circuit.
• Use a multimeter to test the valve's resistance and current draw.
• Replace the coolant control valve B if faulty.
• Repair or replace damaged wiring in the control circuit.
• Replace the control module if necessary.
• OBD-II scanner
• Multimeter
• Wrench set
$200 - $600
Moderate
• Toyota Prius
• Chevrolet Volt
• Nissan Leaf
• Regular maintenance of the cooling system
• Check and replace coolant as needed
• Inspect wiring and connections periodically
Control Circuit Issue
• Do not ignore the warning light; get it checked soon.
• Avoid driving the vehicle aggressively until the issue is resolved.
Check your vehicle's warranty for coverage on hybrid system components.
This code has been reported in hybrid and electric vehicles as they age, often related to cooling system maintenance.
Moderate – Should be addressed soon to prevent battery damage.
Driving with this issue can lead to battery overheating, which may pose a safety risk.
• Vehicle engine is running
• Hybrid/EV system is active
The coolant control valve is typically located near the battery pack or cooling system components.
Q: Can I drive with a P0E21 code?
A: It's not recommended to drive for long with this code, as it may lead to battery overheating.
Q: How can I prevent this issue?
A: Regular maintenance of the cooling system and checking the coolant level can help prevent this issue.
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