What causes fault code P008D?

• Most likely: Short circuit to voltage in the fuel cooler pump wiring harness • Likely: Faulty fuel cooler pump (internal short or open circuit) • Possible: Faulty fuel cooling relay (if equipped) • Rare: Corrosion in the ECM connector or internal ECM failure

How do you fix fault code P008D?

STEP 1: Check fuses related to the fuel system or auxiliary cooling. Inspect the pump connector for signs of melting or corrosion. STEP 2: Measure voltage at the pump connector with the ignition on. If shorted to voltage, you will see 12V+ even when the pump is commanded off. Check ground continuity (should be < 0.5 Ohm). STEP 3: Use a scan tool to perform an output test (bi-directional control). Use an oscilloscope to verify the PWM signal from the ECM. A correct signal should toggle between 0V and battery voltage. STEP 4: If wiring is intact and the ECM signal is correct, but the pump fails to operate or shows abnormal resistance, replace the fuel cooler pump.

Powertrain (Engine & Gearbox)Standard EOBD

P008D - Fuel Pressure Cooler Pump Control Circuit High

Q: What does fault code P008D mean?

P008D is set when the Engine Control Module (ECM) detects an abnormally high voltage signal on the fuel pressure cooler pump control circuit. This circuit controls a dedicated pump used to circulate fuel through a heat exchanger (cooler) to maintain optimal fuel temperature and prevent cavitation or damage to fuel system components. The high signal usually indicates a short circuit to voltage or an open circuit condition where the ECM is unable to pull the control line to ground. The system often employs PWM (Pulse Width Modulation) to regulate pump speed, and any deviation from commanded duty-cycle voltage triggers the MIL (Malfunction Indicator Lamp).

Q: What are the symptoms of fault code P008D?

• Check engine light (MIL) illuminated • Reduced engine performance under heavy load (potential Limp Mode) • Increased fuel temperatures (observable via data stream) • Emissions test failure

Last updated:1 February 2026

Related:Fuel Cooler Pump, ECM (Motorstyrdon), Fuel Temperature Sensor, Kablage och kontaktstycken

System

Powertrain (Engine & Gearbox)

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P0000

No Diagnostic Trouble Codes (DTC) Present

P0001

Fuel Volume Regulator Control Circuit / Open

P0002

Fuel Volume Regulator Control Circuit Range/Performance

P0003

Fuel Volume Regulator Control Circuit Low

Technical Description

P008D is set when the Engine Control Module (ECM) detects an abnormally high voltage signal on the fuel pressure cooler pump control circuit. This circuit controls a dedicated pump used to circulate fuel through a heat exchanger (cooler) to maintain optimal fuel temperature and prevent cavitation or damage to fuel system components. The high signal usually indicates a short circuit to voltage or an open circuit condition where the ECM is unable to pull the control line to ground. The system often employs PWM (Pulse Width Modulation) to regulate pump speed, and any deviation from commanded duty-cycle voltage triggers the MIL (Malfunction Indicator Lamp).

Possible Causes

Short circuit to voltage in the fuel cooler pump wiring harness

Faulty fuel cooler pump (internal short or open circuit)

Faulty fuel cooling relay (if equipped)

Corrosion in the ECM connector or internal ECM failure

Symptoms

Check engine light (MIL) illuminated

Reduced engine performance under heavy load (potential Limp Mode)

Increased fuel temperatures (observable via data stream)

Emissions test failure

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P008D - Fuel Pressure Cooler Pump Control Circuit High

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P008D - Fuel Pressure Cooler Pump Control Circuit High

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