P0308 serious

Cylinder 8 Misfire Detected

What does P0308 mean?

The P0308 code means the vehicle's onboard diagnostic system has detected: Cylinder 8 Misfire Detected. This is a serious severity code.

Common Symptoms

  • Rough idle on V8 engine
  • Check Engine Light on
  • Power loss

Probable Causes (Ranked by Likelihood)

  • Faulty spark plug on cylinder 8 Very High
  • Failed ignition coil on cylinder 8 High
  • Clogged fuel injector on cylinder 8 High
  • Low compression on cylinder 8 Moderate

Step-by-Step Diagnostic Procedure

  1. Swap cylinder 8 coil and spark plug to confirm the misfiring component.

  2. Injector balance test on cylinder 8.

  3. Compression and leak-down test if needed.

Frequently Asked Questions

I have both P0300 and P0308 -- what does that mean?

A random/multiple misfire (P0300) combined with a specific cylinder code (P0308) means the random misfire may be driven primarily by cylinder 8. Fix cylinder 8 first and see if P0300 resolves as well.

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