P01C6

What it means

P01C6 means the engine control unit has seen the signal voltage from fuel pressure sensor 'A' sit higher than its expected range. This is an electrical circuit fault flag, not proof that actual fuel pressure is wrong. Which sensor is 'A', and whether it sits on the low-pressure or high-pressure side, depends on the vehicle and engine, so check the model-specific information.

Symptoms

• Engine warning light on
• Reduced power or limp mode
• Hard starting or long cranking
• Rough idle or hesitation under load
• Stalling or poor running with erratic fuel trims
• Fuel pressure reading on a scan tool stuck at maximum or implausible

Possible causes

• Faulty fuel pressure sensor with an internal fault giving a high outputlikely
• Open circuit or poor connection in the sensor ground or return wire, which pulls the signal highlikely
• Signal wire shorted to the 5 V reference or to battery voltage, caused by chafed or damaged wiringpossible
• Corroded, damaged or loose sensor connector or terminalspossible
• Actual fuel pressure far above the sensor's expected range because of a regulator, pump control or pressure control valve fault (system dependent)possible
• Fault inside the engine control unit or its sensor supplyrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting engine load, rpm and temperature when the fault set, and look for related fuel pressure or supply codes.
2. Check live data for the fuel pressure sensor reading and voltage with the ignition on and engine off, then compare it with the expected pressure and the manufacturer's specification.
3. Inspect the sensor, connector and wiring for damage, chafing, corrosion, fuel contamination, water ingress or poor terminal tension, and wiggle the harness while watching live data.
4. Unplug the sensor and check the 5 V reference, ground and signal circuits against the wiring diagram for the model, looking for shorts to voltage and open circuits.
5. Check the sensor ground and reference circuits for voltage drop under load.
6. Where the system allows, verify actual fuel pressure with a suitable mechanical gauge to separate a real pressure problem from a sensor or circuit fault, following the manufacturer's depressurising procedure for high-pressure systems.
7. If the wiring and pressure are good, test the sensor against specification and only then consider the control unit, after checking for software updates relevant to this fault.

How to fix

• Repair or replace damaged wiring, including any short to voltage or open ground, and secure the harness away from heat and abrasion.
• Clean or replace corroded or damaged connectors and terminals.
• Replace the fuel pressure sensor if it is faulty, using the correct part for the engine and fuel system.
• Correct any real over-pressure fault found, such as a faulty pressure regulator or control valve, as the model requires.
• Update or repair the control unit software or the unit itself only if a confirmed fault or known calibration issue is found.
• Clear the code after repair and road test, confirming the pressure reading is plausible and the fault does not return.

Can I keep driving?

Nearby codes

• P01C5GenericFuel Pressure Sensor A Circuit Low
• P01C7GenericFuel Pressure Sensor A Circuit Intermittent/Erratic