Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This means that a part of the car that helps control the engine's temperature is not working right. It's like a door that should open and close, but it's stuck open.
The coolant bypass valve is responsible for directing the flow of coolant in the engine. If it's stuck open, it can cause the engine to not warm up properly or overheat.
The P0E79 code indicates that the Engine Control Module (ECM) has detected that the Coolant Bypass Valve A is not operating as expected. This valve is crucial for regulating the flow of coolant to ensure optimal engine temperature. A stuck or open valve can lead to inefficient engine performance and potential overheating.
• Check engine light is on
• Engine overheating
• Poor fuel economy
• Faulty coolant bypass valve
• Wiring issues in the valve circuit
• ECM malfunction
ECM: Engine Control Module, the computer that controls engine functions.
Coolant: A fluid that helps regulate engine temperature.
• Use an OBD-II scanner to confirm the code
• Inspect the coolant bypass valve for physical damage
• Check wiring and connections for continuity
• Replace the coolant bypass valve
• Repair or replace damaged wiring
• Reprogram or replace the ECM if necessary
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $500
Moderate
• Toyota Prius
• Chevrolet Volt
• Ford Fusion Hybrid
• Regular maintenance checks
• Ensure proper coolant levels
• Inspect valve operation periodically
Engine Performance
• Do not ignore the check engine light
• Have the vehicle inspected by a professional
• Monitor engine temperature closely
Check with your vehicle manufacturer for warranty coverage on emissions-related components.
This code has been associated with hybrid vehicles where maintaining optimal engine temperature is critical for efficiency.
Moderate – Addressing this issue promptly can prevent further engine damage.
Driving with an unresolved P0E79 code may lead to engine damage and increased emissions.
• Engine at operating temperature
• Coolant system pressurized
The coolant bypass valve is typically located near the engine's thermostat housing.
Q: Can I drive with a P0E79 code?
A: It's not recommended to drive for long periods with this code active, as it can lead to engine overheating.
Q: How can I prevent this issue?
A: Regular maintenance and ensuring proper coolant levels can help prevent this issue.
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Fitment Required · Vehicle-fitment part
Relevant when coolant-temperature and warm-up faults indicate a thermostat-related issue.
Coolant-temperature and warm-up faults often lead to thermostat testing and replacement.
Thermostats are vehicle-specific and should be matched by engine and housing style.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.