Engine

P03E2 — Cylinder 8 Pressure Variation Low

Severity: medium Drive with care, to a shop

What P03E2 means

The engine control module estimates how hard each cylinder is working, often by tracking crankshaft speed changes, and compares that with expected values. P03E2 means cylinder 8 shows less pressure variation than it should. That points to a weak or unstable combustion event, such as a misfire or a mechanical problem in that cylinder. The exact method varies by manufacturer and engine.

Symptoms

  • Check Engine light on
  • Rough idle or engine vibration
  • Reduced power and sluggish acceleration
  • Poor fuel economy
  • Possible hesitation under load

Possible causes

  1. Worn or faulty spark plug in cylinder 8
  2. Faulty ignition coil or coil wiring on cylinder 8
  3. Faulty or clogged fuel injector on cylinder 8
  4. Vacuum leak near that cylinder's intake runner
  5. Low compression in cylinder 8: valve, rings or head gasket
  6. Rarely, an ECM fault or wiring open circuit

How to diagnose

  1. Scan all codes and freeze frame data, and look for cylinder 8 misfire codes
  2. Inspect the cylinder 8 spark plug, checking gap and electrode condition
  3. Swap the cylinder 8 coil with a neighboring one and see if the fault follows
  4. Check the coil and injector connectors and wiring for damage or corrosion
  5. Test the injector: resistance, operating sound, and flow if needed
  6. Check the intake for vacuum leaks, for example with a smoke machine
  7. Run a compression test on cylinder 8, plus a leak-down test if needed
  8. Consider ECM faults only after everything else is ruled out

Common fixes

  • Replace spark plugs, ideally as a full set
  • Replace the faulty cylinder 8 ignition coil
  • Replace or clean the cylinder 8 fuel injector
  • Fix vacuum leaks by replacing damaged hoses or gaskets
  • Repair the engine mechanically based on compression test results
  • Repair damaged wiring or connectors

Questions and answers

What does P03E2 mean?

The ECM found that cylinder 8 has too little pressure variation. It's usually caused by a misfire, an injector problem or a mechanical fault in that cylinder.

Can I drive with code P03E2?

Short, light-load trips are usually okay, but get it fixed soon. If the Check Engine light flashes, stop driving, because the misfire is severe and can ruin the catalytic converter.

Where should I start diagnosing P03E2?

Start with the spark plug and coil on cylinder 8, since they are the most common and cheapest causes. If they check out, move on to the injector, vacuum leaks and compression.

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.