P008E — Fuel Cooler Pump Control Circuit High #

Note: The code description may differ between manufacturers.

• Fuel Cooler Pump Control Circuit High (General, SAE)
• Fuel Cooler Pump Control Circuit High Input (Ford)
• Fuel Cooler Pump Circuit Voltage High (GM)
• Fuel Cooler Pump Signal High (Volkswagen/Audi)

Summary of DTC P008E #

The P008E diagnostic trouble code (DTC) indicates that the fuel cooler pump control circuit is registering a higher than expected voltage. In modern diesel and some gasoline vehicles, a fuel cooler pump is used to circulate fuel through a cooling system to prevent overheating, especially under heavy loads or high ambient temperatures. The Powertrain Control Module (PCM), also called the Engine Control Module (ECM), monitors this circuit for abnormalities. When it detects a voltage reading above the manufacturer’s specified range, it sets the P008E code. This issue is usually electrical and may not immediately affect drivability, but ignoring it can lead to further complications with fuel system performance.

Common Symptoms for Code P008E #

Although P008E often triggers the Check Engine Light without obvious drivability issues, some symptoms may be noticeable depending on the vehicle and the severity of the fault. The fuel cooling system helps maintain optimal fuel temperature, which is crucial for performance and emissions. If the circuit is malfunctioning, symptoms may include:

• Illuminated Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL)
• Possible reduced engine performance under heavy load
• Intermittent hard starting, especially in hot weather
• Increased fuel temperature readings (if equipped with gauge or scan tool)
• Rarely, fuel system warning messages on the dash

Probable Causes for Code P008E (Ranked by Frequency) #

Several issues can trigger a high-voltage condition in the fuel cooler pump control circuit. The most common are electrical faults, but mechanical problems or even software errors can also be responsible. Here are the likely culprits, listed from most to least frequent:

1. Wiring issues: Damaged, shorted-to-power, or corroded wires/connectors in the pump control circuit.
2. Faulty fuel cooler pump: Internal electrical fault causing excessive current draw or short circuit.
3. Defective PCM/ECM: Rare, but a malfunctioning control unit can misinterpret or send incorrect voltage.
4. Poor ground connection: High resistance in the ground path can result in abnormal voltage readings.
5. Aftermarket electrical additions: Incorrectly installed accessories tapping into the circuit.

Step-by-Step Diagnostic for Code P008E #

A systematic approach is essential to accurately identify and resolve the root cause of P008E. Follow these steps to avoid misdiagnosis:

• 1. Confirm the code: Use a professional scan tool to verify P008E is present and check for related codes (especially fuel system or electrical).
• 2. Inspect wiring and connectors: Visually and physically check the fuel cooler pump harness for chafing, corrosion, or damaged insulation.
• 3. Test circuit voltage: With a digital multimeter, measure voltage at the pump connector with ignition ON. Compare with OEM specifications.
• 4. Check pump resistance: Disconnect the pump and measure resistance across its terminals. Excessively low or high resistance indicates internal faults.
• 5. Verify ground integrity: Ensure the pump’s ground wire has minimal resistance to chassis ground.
• 6. Inspect for aftermarket modifications: Look for non-OEM wiring or accessories spliced into the circuit.
• 7. Test PCM/ECM output (if all else checks): If wiring and pump are healthy, check the control unit’s output signal and consider reprogramming or replacement as a last resort.
• 8. Clear the code and retest: After repairs, erase the code and road test to confirm resolution.

Possible Repairs for Code P008E #

Once the underlying cause is identified, repairs should directly address the issue. Always use OEM-quality parts and follow manufacturer guidelines for best results. Repairs may include:

• Repairing or replacing damaged wiring or connectors in the fuel cooler pump circuit
• Replacing a faulty fuel cooler pump
• Securing or remaking a poor ground connection
• Removing or correcting improper aftermarket electrical modifications
• Reprogramming or replacing the PCM/ECM if faulty (very rare)

Is It Safe to Drive With Code P008E? #

Usually yes, but with limitations. In most cases, P008E will not cause immediate drivability issues, and you can continue to drive the vehicle for short distances. However, if you often drive under heavy load, in high temperatures, or tow with your vehicle, ignoring the code could lead to fuel overheating, reduced engine performance, or in rare cases, vapor lock. It is advisable to fix the issue at your earliest convenience to avoid potential long-term damage.

Vehicles Most Commonly Affected by Code P008E #

This DTC is most frequently reported on modern diesel vehicles equipped with fuel cooling systems, but is also found on some high-performance gasoline engines. The following applications are often affected:

• Ford Super Duty trucks (diesel engines, 2011+)
• GM Duramax-equipped trucks (Chevrolet Silverado, GMC Sierra)
• Volkswagen and Audi TDI models
• Land Rover and Jaguar diesel SUVs
• RAM trucks with Cummins diesel engines

Note: This is not an exhaustive list, and the code may appear on other vehicles with fuel cooler pumps.

Common Mistakes & Best Practices for Code P008E #

Proper diagnosis of P008E requires attention to detail. Avoid these common mistakes and follow best practices to ensure a lasting repair:

• Assuming the fuel cooler pump is faulty without first checking wiring and connectors
• Overlooking ground connections, which are a frequent source of high voltage readings
• Ignoring service bulletins or updated wiring diagrams from the OEM
• Resetting the code without addressing the root cause
• Failing to inspect for aftermarket electrical work that could affect the circuit

Quick FAQ for Code P008E #

Q: Can I just clear the code and keep driving?
A: Clearing the code may temporarily turn off the Check Engine Light, but if the underlying problem isn’t fixed, the code will return. Persistent high fuel temperatures can harm long-term reliability.

Q: Does this mean my engine will overheat?
A: Not directly. This code relates to the fuel cooling system, not the engine’s coolant circuit. However, high fuel temperatures can affect performance and, in rare cases, cause hard starting or fuel system issues, especially under heavy load.

If you have further questions, always consult a qualified technician or refer to your vehicle’s official service information for guidance.