P008BPowertrain
Powertrain · SAE
Low Fuel Pressure — Low Pressure Side Too High
Meaning
Pressure in the low-pressure circuit is above the maximum expected threshold. The ECM detects abnormally high pressure upstream of the high-pressure pump, which can indicate a faulty return-circuit pressure regulator.
Common causes
- Return circuit pressure regulator stuck or faulty
- Partial obstruction in the fuel return circuit
- Low-pressure sensor failed or drifting high
- Faulty pressure valve integrated in the pump
- Sensor wiring shorted to supply voltage
Symptoms
- Check-engine light on
- Possible idle irregularity
- Increased fuel consumption
- Signs of over-pressure in the low-pressure circuit
- Rarely obvious drivability symptoms
Severity
Moderate: overpressure in the low-pressure side can damage seals and the pump over time; diagnose and repair.
What to do
- Measure actual low-pressure circuit pressure with an external gauge
- Check the return-circuit pressure regulator operation
- Inspect the fuel return circuit for obstructions
- Check the low-pressure sensor for calibration drift
- Replace the regulator or sensor based on findings