Engine

P03DE — Cylinder 8 Pressure Sensor Circuit High

Severity: medium Drive with care, to a shop

What P03DE means

The engine control unit is reading a voltage from the cylinder 8 pressure sensor that is higher than the expected range. This sensor measures combustion pressure in the cylinder, and the ECM uses it to judge combustion quality and adjust engine control. A high signal usually points to a bad sensor or a wiring or connector fault, and less often to the ECM input.

Symptoms

  • Check Engine Light on
  • Rough or uneven idle
  • Reduced engine power
  • Higher fuel consumption
  • Vibration under load

Possible causes

  1. Failed cylinder 8 pressure sensor
  2. Damaged wiring or a short to voltage in the sensor circuit
  3. Corroded or loose connector terminals
  4. ECM input circuit fault
  5. Mechanical problem in cylinder 8 affecting pressure (uncommon)

How to diagnose

  1. Scan all codes and freeze frame data, noting any other cylinder-related codes
  2. Inspect the cylinder 8 sensor harness and connector for chafing, oil, corrosion and bent pins
  3. Watch the sensor reading live on a scan tool
  4. Unplug the sensor and see whether the reading or code changes
  5. Check reference voltage, supply and ground at the connector using the wiring diagram
  6. Test the signal wire for opens and shorts to voltage
  7. Compare with the sensor on a neighboring cylinder if possible
  8. If wiring and sensor test good, evaluate the ECM

Common fixes

  • Repair damaged wiring and clean or replace the connector
  • Replace the cylinder 8 pressure sensor
  • Repair or replace the ECM if it has an internal fault
  • Clear codes and road test to confirm the repair

Questions and answers

What does P03DE mean?

It means the ECM sees a high signal in the cylinder 8 pressure sensor circuit. The cause is usually the sensor, wiring or a connector.

Can I drive with P03DE?

For a short time, yes, but diagnose it soon. You may notice rough running, lost power and worse fuel economy.

How do I fix P03DE?

Start with the wiring and connector at the sensor, then test or replace the sensor. ECM replacement is rarely needed and only after ruling out everything else.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.