GMC Terrain · Diagnostic Trouble Code
P0303 — Cylinder 3 Misfire Detected
Quick overview of P0303 on your GMC Terrain. Read the full diagnosis guide, then find the repair guides for your vehicle below.
Repair guides that fix P0303
GMC Terrain
2018-2024 GMC Terrain — Spark Plug Replacement
The most common misfire fix: a fresh set of plugs.
GMC Terrain
2018-2024 GMC Terrain — Replace Ignition Coil
How to test and replace a bad coil pack.
GMC Terrain
2018-2024 GMC Terrain — Check Engine Light / OBD2 Diagnosis
What that light means and what to check first.
General diagnostic information, not a factory service procedure. If you're unsure, have a qualified technician confirm the diagnosis before buying parts.