P008D — Fuel Cooler Pump Control Circuit Low

OBD2 code P008D flags a problem with the sensor and actuator circuits (fuel cooler pump control circuit low). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, blown fuse feeding the circuit, corroded, loose or damaged connector.

powertrain (engine/transmission)

Is it safe to drive?

Drive cautiously while diagnosing P008D P008D does not always prevent operation, but continued driving with an inoperative fuel cooling pump can allow fuel temperature to rise, especially during heavy load. Address the fault promptly and stop if fuel-temperature or overheating warnings appear.

Typical symptoms

P008D remains stored in the powertrain control module
The check-engine light may illuminate
The ECM may command the fuel cooler pump but detect inadequate circuit voltage
Fuel temperature may rise faster than expected under sustained load
The fuel cooling system may operate intermittently
A higher-than-normal fuel temperature warning may appear on some vehicles

Common causes

An open or high-resistance connection in the fuel cooler pump control circuit
A failed fuel cooler pump relay or control solenoid
A defective fuel cooler pump with excessive electrical resistance
A blown or improperly rated fuse in the fuel cooler pump power circuit
Corroded terminals, damaged wiring, or a poor ground at the control module
A short to ground in the control wiring
An ECM driver failure involving the P008D control output

How to diagnose with an OBD scanner

Confirm P008D with an OBD scanner Connect an ELM327 adapter or AIScanAuto, select the powertrain control module, and confirm that P008D is stored or currently active. Review freeze-frame and live data for fuel temperature, pump command, and circuit feedback before disconnecting components.
Inspect the control circuit With the ignition off, trace the fuel cooler pump wiring and inspect the connector, relay, and fuse for corrosion, heat damage, loose terminals, or broken conductors. Repair damaged wiring and clean or replace unreliable connections.
Check voltage and continuity Use the vehicle wiring diagram to identify the P008D control output. With the engine running and the pump commanded on, measure voltage at the relay or actuator and compare it with the specified value. Also check for continuity to ground if the output is not pulling down correctly.
Test the relay and pump or solenoid Verify the relay receives power and ground and that it switches as commanded. Test the fuel cooler pump or control solenoid for continuity and excessive resistance; a windings failure can make the control circuit read abnormally low.
Verify operation and clear P008D After repairs, confirm the pump runs when commanded and that fuel-temperature data responds appropriately. Clear P008D with the scanner, operate the vehicle through a complete drive cycle, and verify that the code does not return.

Approximate repair cost

Typical independent-shop repair estimates for P008D are approximately $150-$600 USD, depending on whether the repair involves a relay, wiring repair, pump, or control-module diagnosis. These figures are estimates and vary by region.

Common questions

What does P008D mean?

P008D means the powertrain control module detected low voltage in the fuel cooler pump control circuit. The fault may involve the pump, relay, wiring, connectors, grounds, or the control output.

Can I drive my vehicle with P008D stored?

The vehicle may still drive, but fuel cooling may be reduced and fuel temperature can rise during sustained operation. Repair the issue promptly and avoid heavy driving if a fuel-temperature warning appears.

What should I check first when P008D appears?

Start by confirming the code and freeze-frame data with an OBD scanner, then inspect the pump relay, fuse, connectors, and wiring. A low-circuit signal frequently results from an open connection or failed relay.

Does P008D require replacing the fuel cooler pump?

Not necessarily. Testing the relay, control output, grounds, and wiring may identify a less expensive fault. Replace the pump only when electrical testing shows that its motor or windings are defective.

When your scan tool displays P008D, the engine computer has identified that the electrical circuit responsible for the fuel cooler pump is exhibiting abnormally low voltage. This code belongs to the powertrain category and specifically targets the control and feedback circuits that manage fuel temperature regulation. The term "circuit low" tells you that whatever signal should be pulsing through this pathway is instead sitting near ground potential, essentially shorted out or starved of proper electrical current.

The fuel cooler pump plays a supporting role in managing fuel temperature, particularly in vehicles that operate under heavy loads or in extreme conditions where fuel can heat up significantly. When the engine control module commands this pump to activate, it expects to see a specific voltage response on the control circuit. If that voltage never reaches the required threshold, P008D triggers. The control module typically monitors this condition across multiple drive cycles before confirming the fault, which helps filter out temporary electrical glitches from genuine failures. When the code sets, the module also captures a freeze frame snapshot containing engine speed, load percentage, coolant temperature, and vehicle speed at the exact moment the fault occurred—valuable information that points you toward the root cause.

Understanding why the voltage stays low requires examining the physical side of the circuit. A wire rubbing against metal can wear through its insulation and create a direct short to ground. Corrosion at a connector can increase resistance until the signal collapses entirely. The pump motor itself can fail in ways that drag the circuit low, or a power supply feeding the circuit might simply be absent due to a blown fuse. Each of these failure modes produces the same diagnostic result: the control module sees insufficient voltage and records P008D.

Symptoms

The Check Engine light will illuminate when P008D becomes active, serving as your first indication that something is wrong. In many vehicles, the fuel cooler system will stop functioning or operate only intermittently, since the control module can no longer reliably communicate with the pump. Fuel economy may climb slightly in some cases, as the engine adapts to missing feedback from the affected circuit. Depending on how the manufacturer programmed the control strategy, you might experience reduced performance modes or "limp home" behavior that limits power to protect components. The severity of symptoms varies considerably based on your specific vehicle and how dependent the engine management system is on fuel cooler operation.

Causes

The most frequent culprits behind P008D are damaged wiring and poor electrical connections in the fuel cooler pump circuit. A chafed wire touching ground, corroded pins inside a connector, or a loose plug can all produce the low voltage condition the code describes. Failed fuel cooler pumps themselves rank second, particularly the electrical windings or internal contacts that carry the control signal. Missing supply voltage from a blown fuse or broken power wire also commonly triggers this fault, since the pump cannot operate without proper battery voltage feeding it. Faulty sensors or actuators within the circuit can fail in ways that short the signal line to ground. Control module driver failures are less common but possible, where the module's own output circuitry malfunctions. Finally, open or high-resistance wiring anywhere in the harness can prevent the signal from reaching its intended destination.

Diagnosis

Begin by connecting your OBD2 scanner and confirming that P008D is stored in the engine control module memory. Record all available freeze frame data before clearing anything—this snapshot tells you exactly what conditions existed when the fault occurred. Look for any related diagnostic trouble codes that might point toward a broader electrical issue or a specific circuit requiring attention. Checking manufacturer technical service bulletins for your vehicle can save hours of diagnostic work, as many code patterns have documented factory fixes or software calibrations available.

Visually inspect the wiring harness routing near the fuel cooler pump and its connectors. Look for wires that have chafed against bodywork, melted sections near heat sources, or damage from road debris. Wiggle the connectors while monitoring live data on your scanner—if the signal drops out during movement, you have located an intermittent connection. Check for battery voltage at the pump's power supply circuit, then measure resistance from the signal wire to ground. A reading near zero ohms confirms a short to ground in the harness. Test ground circuit continuity at the pump connector, ensuring the module has a reliable return path. After repairs or if no faults are found, clear the code and drive the vehicle through conditions matching the freeze frame data to verify the problem does not return.

Repair Options

Addressing the most likely causes first keeps costs reasonable. Wiring harness repair or connector replacement typically runs between $80 and $250 depending on accessibility and the extent of damage. If testing confirms the fuel cooler pump motor or its associated sensors have failed, replacement parts and labor generally fall between $150 and $500. Control module repair or replacement represents the most expensive scenario, ranging from $300 to $1,000 depending on whether the module can be rebuilt or requires ordering a new unit programmed for your vehicle.

Cost Summary

Total repair expenses for P008D usually span $80 to $1,000 when accounting for parts and labor at independent shop rates. The wide range reflects how different vehicles handle fuel cooler control—some require simple connector cleaning while others need complete harness replacement. An accurate diagnosis before purchasing components prevents spending money on unnecessary parts. Most shops will charge a standard diagnostic fee to perform the voltage and resistance checks that pinpoint the actual failure, which is money well spent before committing to repairs.

Can You Drive With P008D?

Most vehicles remain driveable when P008D is active, though you may notice slight performance limitations or warning indicators depending on how heavily your engine management system relies on the fuel cooler circuit. If the car runs normally otherwise, you can schedule repairs at your convenience within days rather than hours. However, take a more urgent approach if the vehicle exhibits stalling, failure to start, or warnings related to braking and steering systems—these conditions warrant immediate professional attention regardless of what the scan tool shows.