Engine

P03E3 — Cylinder 8 Pressure Variation Too High

Severity: medium Drive with care, to a shop

What P03E3 means

P03E3 sets when the cylinder pressure data shows that combustion pressure in cylinder 8 varies too much from one cycle to the next. Normally each cylinder burns consistently and peak pressure stays fairly steady. Instability points to a fuel, ignition, sealing or airflow problem affecting that cylinder.

Symptoms

  • Check Engine light on
  • Rough idle or vibration
  • Loss of power and sluggish acceleration
  • Worse fuel economy
  • Possible hesitation under load

Possible causes

  1. Faulty cylinder 8 fuel injector (leaking or clogged)
  2. Worn spark plug or failing ignition coil on cylinder 8
  3. Low compression: valves, piston rings or head gasket
  4. Vacuum leak or uneven airflow in the intake
  5. Faulty cylinder pressure sensor, its wiring, or an ECM fault

How to diagnose

  1. Scan all codes and freeze frame data, and look for misfire codes such as P0308
  2. Inspect the wiring and connectors of the pressure sensor and cylinder 8 coil
  3. Check the cylinder 8 plug and coil; swap the coil with a neighbor to see if the problem follows
  4. Test the cylinder 8 injector operation and fuel pressure
  5. Look for vacuum leaks with a smoke machine and review fuel trims
  6. Run a compression and cylinder leak-down test
  7. Suspect the sensor or ECM only after the above is ruled out

Common fixes

  • Replace the cylinder 8 spark plug and/or ignition coil
  • Replace or clean the cylinder 8 fuel injector
  • Repair intake or vacuum leaks
  • Repair internal engine problems (valves, rings, head gasket)
  • Replace the faulty sensor or wiring; diagnose the ECM if confirmed

Questions and answers

What does P03E3 mean?

It means combustion pressure in cylinder 8 is too inconsistent from cycle to cycle. The cause can be spark, fuel, compression or airflow.

Can I drive with P03E3?

Only briefly and gently, for example to a shop. If the engine shakes badly or the check engine light flashes, stop to avoid damaging the catalytic converter.

What should I check first?

Start with the cylinder 8 spark plug and coil, then the injector and any vacuum leaks. If those are fine, do a compression test.

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.