P02E8

What it means

P02E8 means the engine control unit has detected a low voltage signal from the position sensor for the diesel intake air flow control (typically the intake throttle or air flow valve, circuit A). The signal has dropped below the expected range, which suggests a short to earth, an open circuit, or a faulty sensor. The control unit can no longer trust the valve position, so it may limit performance.

Symptoms

• Engine warning light on
• Reduced power or limp mode
• Poor or uneven idle
• Engine stalling or hesitation on acceleration
• Rough running or increased smoke
• Difficulty starting or unexpected shutdown

Possible causes

• Faulty position sensor within the intake air flow valve or throttle actuatorlikely
• Damaged, chafed or corroded wiring to the position sensor, causing a short to earth or open circuitlikely
• Poor connection or corroded terminals at the actuator or control unit connectorlikely
• Sensor reference supply (5 V) fault or short to earth, possibly shared with other sensorspossible
• Valve mechanically stuck or heavily sooted, affecting the position feedbackpossible
• Faulty engine control unitrare

How to diagnose

1. Read all stored and pending codes and note the freeze frame data, including engine speed, load and temperature, to see when the fault set.
2. Check for other codes on the sensor reference supply or related circuits, as a shared supply fault points away from a single sensor.
3. Visually inspect the intake air flow valve or throttle actuator, its wiring and connector for damage, heat, oil or water ingress and corrosion.
4. Using live data, compare the commanded and actual valve position while operating the actuator with the scan tool, and check it moves smoothly through its range.
5. With the ignition on, check the reference supply voltage and earth at the sensor connector against the manufacturer's data for your model.
6. Check the signal wire for continuity and for a short to earth between the connector and the control unit, with the connectors disconnected.
7. Inspect the valve for carbon build-up or a stuck mechanism, following the model-specific procedure.
8. If wiring and sensor tests are good, check for software updates relevant to your model before considering control unit faults.

How to fix

• Repair or replace damaged wiring and fix any short to earth or open circuit found.
• Clean or replace corroded connector terminals and secure the connector properly.
• Replace the intake air flow valve or throttle actuator if the position sensor is faulty, then carry out any required adaptation or learning procedure.
• Clean a sooted or sticking valve where the manufacturer allows it, otherwise replace it.
• Repair the sensor reference supply fault if one is found.
• Repair or replace the control unit only after all other causes are ruled out, and only where confirmed faulty.

Can I keep driving?

Nearby codes

• P02E7GenericDiesel Intake Air Flow A Position Sensor Circuit Range/Performance
• P02E9GenericDiesel Intake Air Flow A Position Sensor Circuit High