Engine

P03A7 — Cylinder 2 Pressure Variation Too High

Severity: medium Drive with care, to a shop

What P03A7 means

P03A7 means the engine control module saw cylinder 2 pressure vary too much from one combustion cycle to the next. The ECM judges this either from crankshaft speed fluctuations or from an in-cylinder pressure sensor where fitted. Unstable pressure points to uneven combustion caused by misfire, poor fuel delivery or a mechanical problem in that cylinder.

Symptoms

  • Check Engine light on
  • Rough idle or vibration
  • Loss of power under load
  • Higher fuel consumption
  • Possible hard starting

Possible causes

  1. Faulty or clogged fuel injector on cylinder 2
  2. Ignition misfire from a spark plug or coil on cylinder 2
  3. Low compression or mechanical fault in cylinder 2 (valves, piston rings, head gasket)
  4. Fault in the cylinder pressure sensor or its wiring

How to diagnose

  1. Scan all codes and freeze frame data, and look for misfire codes such as P0302
  2. Inspect the cylinder 2 spark plug for wear, carbon, oil or fuel fouling
  3. Swap the cylinder 2 coil with a neighbor and see if the fault follows
  4. Test the injector: resistance, operation, balance or flow
  5. Check wiring and connectors for the pressure sensor (if fitted), injector and coil
  6. Run a compression or leak-down test on cylinder 2
  7. Check for vacuum leaks and fuel pressure

Common fixes

  • Replace or clean the cylinder 2 fuel injector
  • Replace the spark plug and/or ignition coil on cylinder 2
  • Repair the engine mechanical fault (valves, piston, head gasket)
  • Repair wiring or replace a faulty sensor

Questions and answers

What does P03A7 mean?

The ECM detected too much pressure variation in cylinder 2. It is most often caused by misfire, a bad injector or a mechanical problem in that cylinder.

Can I drive with P03A7?

Only briefly and under light load to reach a repair shop. Continued misfire can ruin the catalytic converter and damage the engine.

Where should I start diagnosing P03A7?

Start with the cylinder 2 spark plug and coil since they are cheap and easy to check. Then move on to the injector and a compression test if needed.

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.