P008E
Fuel Cooler Pump Control Circuit HighP008E is a generic OBD-II powertrain diagnostic trouble code: Fuel Cooler Pump Control Circuit High. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P008E means
Code P008E is the high-voltage counterpart to P008D. It is set when the PCM detects a voltage on the fuel cooler pump control circuit that exceeds the expected operating range. The fuel cooler pump reduces return-fuel temperature by circulating coolant through a heat exchanger before the fuel re-enters the tank or low-pressure supply circuit. A high-circuit condition typically means the control or feedback line has been pulled up to battery voltage through a short to power, or that an internal PCM driver fault is holding the line high when it should be low. On some platforms the PCM uses a pulse-width-modulated signal to vary pump speed; a stuck-high signal can cause the pump to run continuously at full speed or, paradoxically, not respond at all depending on circuit topology. Continuous full-speed operation can overheat the pump motor, while no operation allows return-fuel temperatures to climb. The code is generic SAE and applies to any OBD-II vehicle equipped with an active fuel cooling loop, though diesel platforms are most commonly affected.
Common causes
Most-frequently reported root causes when P008E is logged.
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1
Short to voltage (battery or ignition supply) on the pump control signal wire
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2
Damaged wiring insulation causing the control wire to contact a power source in the harness
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3
Faulty PCM output driver that holds the pump control line permanently high
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4
Corroded or bridged connector pins creating an unintended connection to a high-voltage circuit
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5
Incorrect aftermarket wiring or pump replacement with wrong specification components
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6
Failed pump motor with internal short pulling feedback voltage high
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7
Relay contact welded closed, continuously supplying full voltage to the circuit
Symptoms drivers notice
How to diagnose P008E
A typical diagnostic flow when this code is present.
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1
Retrieve all stored DTCs and review freeze-frame data; note whether P008D and P008E appear together, which may indicate an intermittent short or a PCM driver fault
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2
Inspect the fuel cooler pump harness and connectors for chafing, pinching against hot or moving components, or contact with power wiring that could cause a short to voltage
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3
With the ignition off, disconnect the pump connector and measure voltage at the control wire — any voltage present with the pump disconnected and ignition off indicates a short to power
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4
Check the pump relay: remove it and measure voltage on the circuit-side terminal; a relay with welded contacts will show battery voltage continuously
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5
With the scan tool, command the pump off and observe the live voltage signal; if the voltage remains high, the fault is upstream of the pump (PCM, wiring, or relay)
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6
Perform a PCM-side pin-out test per the vehicle service manual to verify the output driver is not internally shorted high
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7
Repair any shorted wiring or replace faulty relay/connector; if wiring and relay are sound, PCM replacement or reprogramming may be required
Related powertrain codes
Frequently asked questions
What is the difference between P008D and P008E?
P008D indicates the circuit voltage is too low (open circuit, blown fuse, failed pump drawing too much current), while P008E indicates the voltage is too high (short to power, welded relay, or PCM driver fault holding the line high).
Can P008E cause the fuel cooler pump to run all the time?
Yes. If the control line is shorted to battery voltage, the pump may run continuously regardless of PCM commands, which can overheat the pump motor and shorten its service life.
Is P008E a PCM fault or a wiring fault?
Most commonly it is a wiring fault — a short to voltage in the harness. However, if wiring inspection finds no short, a failed PCM output driver is a valid secondary cause and should be tested per the vehicle service manual.
Do I need a dealer scan tool to diagnose P008E?
A professional-grade OBD-II scan tool that can read live PIDs and bi-directional control of the fuel cooler pump is recommended. Dealer or OEM-level tools provide the most precise control commands, but many aftermarket professional tools are capable.
Disabling P008E in software
RaceTune can permanently disable P008E — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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