P008E - Fuel Cooler Control Circuit High
Last updated:
System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P008E indicates that the Engine Control Module (ECM) has detected an abnormally high voltage within the fuel cooler control circuit. Modern diesel and high-performance gasoline engines utilize a fuel cooler to lower the temperature of the return fuel before it reaches the fuel tank. This protects plastic fuel lines and helps maintain fuel density and viscosity. The ECM typically controls this secondary cooling circuit via an electric pump or a bypass valve using a PWM signal. If the signal feedback shows a voltage above the calibrated threshold (often indicating a short to power or a high-resistance open circuit), P008E is triggered.
Possible Causes
Short to voltage in the wiring harness for the fuel cooler pump or valve
Faulty control component (e.g., fuel cooler pump or solenoid) with internal electrical failure
Corroded or damaged connectors causing high resistance/cross-talk
Internal Engine Control Module (ECM) failure
Symptoms
Recommended Solution
- Visual inspection: Check wiring and connectors near the fuel cooler for chafing, corrosion, or burnt pins.
- Fuse check: Verify relevant fuses for the fuel/cooling management system.
- Measurement (Multimeter): Disconnect the component and check voltage on the control wire with ignition on. It should not show constant 12V if the ECU is not commanding activation. Check component resistance (e.g., pump motor); typically 5-30 Ohms.
- Functional test: Use a scan tool to bidirectionally control the fuel cooler component and monitor duty cycle or voltage drop.
- Replacement: Replace the fuel cooler pump or valve if internal electrical failure is confirmed.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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