P0312 - Cylinder 12 Misfire Detected

Cylinder 12 is misfiring often enough for the ECM to detect it.

Treat the code as the starting point: compare symptoms, likely causes, and repair paths before pricing parts or moving into an estimate.

Code Overview

Cylinder 12 is misfiring often enough for the ECM to detect it.

Common Causes

• Worn spark plug on cylinder 12
• Weak ignition coil or boot on cylinder 12
• Fuel injector problem on cylinder 12
• Low compression on cylinder 12

Diagnostic Steps

1. Swap the coil or plug with another cylinder if possible
2. Inspect the spark plug for wear, oil, or fuel fouling
3. Check injector operation and connector fit
4. Run compression or leak-down testing if the misfire stays put

Likely Repairs & Cost Guides

Use symptoms, scan data, and quick checks to confirm the likely repair path before pricing parts. The estimator helps compare repair paths before replacing anything unnecessarily.

Related OBD Codes

Browse nearby code-family pages when the same fault pattern overlaps across systems, such as misfire, lean fuel trim, EVAP sealing, cooling, or charging faults.

Next Steps

Move from code lookup to diagnosis, then estimate the likely repair only after symptoms, causes, and checks point to the same path.