Fuel and air

P02A8 — Cylinder 4 Injector Restricted

Severity: medium Drive with care, to a shop

What P02A8 means

The engine control module has determined that the cylinder 4 injector is delivering less fuel than commanded for its pulse width. This usually shows up in fuel trims and uneven cylinder contribution. The cylinder runs lean, which makes the engine run rough.

Symptoms

  • Check Engine light on
  • Rough or uneven idle
  • Hesitation or stumbling on acceleration
  • Loss of power
  • Higher fuel consumption
  • Possible cylinder 4 misfire

Possible causes

  1. Clogged or carbon-fouled cylinder 4 injector
  2. Internal mechanical or electrical injector fault
  3. Damaged wiring or poor connector contact at the injector
  4. Low fuel pressure from a clogged filter or weak pump
  5. Intake air leak skewing the mixture
  6. ECM software or calibration issue (rare)

How to diagnose

  1. Scan all codes and freeze frame data, and look for misfire codes
  2. Review short-term and long-term fuel trims at idle and under load
  3. Compare cylinder balance or per-cylinder contribution
  4. Inspect the cylinder 4 injector connector and harness, and measure injector resistance
  5. Test fuel pressure and pressure hold after shutdown
  6. Check the intake system and vacuum hoses for leaks
  7. Swap the cylinder 4 injector with a neighbor and see whether the problem follows it
  8. Bench test the injector for flow, spray pattern and leakage

Common fixes

  • Professionally clean the injector or replace it
  • Repair the injector wiring or connector
  • Replace the fuel filter and fix the cause of low pressure
  • Repair any intake air leak
  • Update the ECM software if the manufacturer offers a fix

Questions and answers

What does P02A8 mean?

The ECM sees that the cylinder 4 injector is flowing less fuel than it should. A clogged injector is the most common cause, but wiring and fuel pressure should be checked too.

Will fuel injector cleaner fix P02A8?

A fuel additive may help with light deposits, but a heavily clogged injector is better cleaned on a bench. If the code returns, replace the injector.

Is it safe to drive with this code?

Only for a short time. A lean cylinder can misfire, overheat and damage the catalytic converter, so diagnose it soon.

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.