Engine

P03D5 — Cylinder 7 Pressure Sensor Circuit Intermittent/Erratic

Severity: medium Drive with care, to a shop

What P03D5 means

Some engines use in-cylinder pressure sensors so the ECM can monitor combustion and fine-tune fueling and ignition timing. P03D5 sets when the signal from the cylinder 7 sensor drops out or jumps around instead of following the expected pattern. The ECM then has unreliable combustion data for that cylinder.

Symptoms

  • Check Engine light on
  • Rough idle
  • Engine vibration or hesitation
  • Loss of power
  • Poor fuel economy
  • Intermittent misfires

Possible causes

  1. Failed cylinder 7 pressure sensor
  2. Damaged wiring: chafed, broken or shorted wires
  3. Corroded or loose sensor connector
  4. Poor ground or sensor supply voltage problem
  5. Electrical noise on the signal wire
  6. ECM fault (rare)

How to diagnose

  1. Scan all codes and freeze-frame data, noting any misfire, ignition or power supply codes
  2. Inspect the cylinder 7 sensor connector and harness for chafing, oil, corrosion and heat damage
  3. Wiggle the harness and connector with the engine running while watching sensor data on a scan tool
  4. Test sensor supply, ground and signal wires with a multimeter per the factory diagram
  5. Check the wires for opens and shorts to ground or voltage
  6. Compare the reading with neighboring cylinder sensors
  7. Check sensor mounting and condition, and swap in a known good unit if possible
  8. Suspect the ECM only after everything else checks out

Common fixes

  • Clean or replace the sensor connector
  • Repair or replace the damaged wiring harness
  • Replace the cylinder 7 pressure sensor
  • Restore the sensor ground and supply circuits
  • Diagnose, repair or replace the ECM as a last resort

Questions and answers

What does P03D5 mean?

The ECM detected an unstable signal in the cylinder 7 pressure sensor circuit. Wiring, the connector or the sensor itself is the most common cause.

Can I drive with P03D5?

Short trips to a shop are possible if the engine runs smoothly. If you have misfires or power loss, avoid driving to protect the catalytic converter.

Should I replace the sensor right away?

No. Check the connector and wiring first, because intermittent signals are often caused by a poor connection rather than a failed sensor.

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.