P0204 serious

Injector Circuit Malfunction - Cylinder 4

What does P0204 mean?

The P0204 code means the vehicle's onboard diagnostic system has detected: Injector Circuit Malfunction - Cylinder 4. This is a serious severity code.

Common Symptoms

  • Check Engine Light on
  • Cylinder 4 misfire
  • Rough idle
  • Power loss
  • Unburned fuel smell

Probable Causes (Ranked by Likelihood)

  • Open or shorted cylinder 4 injector circuit Very High
  • Failed injector on cylinder 4 High
  • Damaged harness connector at cylinder 4 High
  • PCM injector driver fault for cylinder 4 Moderate

Step-by-Step Diagnostic Procedure

  1. NOID light on cylinder 4 injector connector while cranking.

  2. Injector resistance test.

  3. Wiring continuity from injector to PCM.

  4. Swap with a known-good injector from another cylinder and see if code follows.

Frequently Asked Questions

Is it safe to run a 4-cylinder engine with one injector not firing?

No. Running on 3 cylinders sends unburned fuel into the exhaust, rapidly overheating and destroying the catalytic converter. A misfiring cylinder is also hard on the engine mechanically.

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