P01C3

What it means

P01C3 means the engine control unit has detected a fault in the circuit of fuel pressure sensor A. The signal voltage or behaviour was outside the expected range, or did not agree with other data such as commanded pressure or engine state. Which sensor 'A' refers to (rail, low-pressure side or other) depends on the engine and model.

Symptoms

• Engine warning light on
• Hard starting or long cranking
• Rough running, hesitation or poor power
• Limp mode or reduced power
• Intermittent stalling or misfire
• Poor fuel economy

Possible causes

• Faulty fuel pressure sensor A giving an incorrect or out-of-range signallikely
• Damaged, chafed or corroded wiring to the sensor (open circuit, short to ground or short to voltage)likely
• Poor connection at the sensor or control unit connector (loose, corroded or pushed-out pin)likely
• Fault in the sensor 5 V reference or ground supply, possibly shared with other sensorspossible
• Real fuel pressure problem (weak pump, restricted filter, leaking or faulty regulator or pressure control) making the reading implausiblepossible
• Low or unstable battery or system voltage affecting sensor readingsrare
• Internal fault in the engine control unitrare

How to diagnose

1. Read all stored and pending codes and note the freeze frame data (engine speed, load, coolant temperature, fuel pressure) to see when the fault set.
2. Look for other codes, especially other sensor reference voltage faults or fuel pressure regulation codes, and deal with those in a sensible order.
3. Visually inspect the sensor, its connector and the wiring along its route for damage, chafing, heat damage, fluid contamination or corrosion.
4. With the ignition on and engine off, view live fuel pressure data and check it reads plausibly, and that it responds sensibly when the engine is started.
5. Check the sensor supply, ground and signal circuits with a multimeter against the manufacturer's wiring diagram and specified values, and wiggle-test the harness while watching the reading.
6. Check battery and charging voltage to rule out low-voltage effects.
7. Measure actual fuel pressure with a suitable mechanical gauge or approved method and compare it with the live data reading. Take care, as many systems run at very high pressure and must be depressurised first.
8. Check fuel level, fuel quality and filter condition, following the model-specific procedure for your engine.

How to fix

• Repair or replace damaged wiring and terminals in the sensor circuit.
• Clean or refit connectors and replace any with corroded, loose or damaged pins.
• Replace fuel pressure sensor A if it is confirmed faulty, following the manufacturer's procedure for depressurising and sealing.
• Repair the cause of any real pressure fault, such as the fuel pump, filter, regulator or pressure control device.
• Repair any reference voltage, ground or charging system fault found during testing.
• Replace the control unit only after all other causes are ruled out and the fault is confirmed.

Can I keep driving?

Nearby codes

• P01C2GenericFuel Rail Pressure Sensor Circuit Intermittent/Erratic Bank 2
• P01C4GenericFuel Pressure Sensor A Circuit Range/Performance