P0312 - Cylinder 12 Misfire Detected

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

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 test results to confirm the fault before pricing the repair.

Related OBD Codes

Browse the closest code-family pages when the same fault pattern often shows up nearby.

Next Steps

Move from the code to a diagnosis path, then into repair pricing once the fault is confirmed.