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 there is a problem with the part of the car that controls how the coolant flows. It's like a gate that isn't opening or closing properly.
The P0E77 code indicates that the control circuit for the coolant bypass valve 'A' is experiencing a high voltage condition.
The coolant bypass valve is responsible for directing the flow of coolant in the engine. When the control circuit for this valve registers a voltage higher than expected, the engine control module (ECM) triggers the P0E77 code. This could be due to a short circuit, a faulty valve, or an issue with the wiring.
• Check Engine Light is on
• Engine overheating
• Poor engine performance
• Faulty coolant bypass valve
• Short circuit in the wiring
• Faulty ECM
ECM: Engine Control Module
OBD-II: On-Board Diagnostics II
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage.
• Test the coolant bypass valve for proper operation.
• Replace the coolant bypass valve if faulty.
• Repair or replace damaged wiring or connectors.
• 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 wiring for wear and tear
Sensor Issue
• Do not ignore the Check Engine Light.
• Get the vehicle inspected by a professional if unsure.
• Regularly check coolant levels.
Check your vehicle's warranty for coverage on engine components.
This code has been more common in hybrid vehicles due to their complex cooling systems.
Moderate – Addressing this issue promptly can prevent engine overheating.
Ignoring the Check Engine Light can lead to more severe engine damage and potential safety hazards.
• Engine at operating temperature
• Vehicle stationary
The coolant bypass valve is typically located near the engine block or radiator.
Q: Can I drive with a P0E77 code?
A: It's not recommended as it can lead to engine overheating.
Q: How do I reset the P0E77 code?
A: Fix the underlying issue, then use an OBD-II scanner to clear the code.
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