P0312 — Cylinder 12 Misfire Detected
High severityWhat it means
P0312 means the engine control unit counted repeated misfires in cylinder 12 specifically. Because it is isolated to one cylinder, the cause is usually a part that serves only cylinder 12 — its spark plug, ignition coil or injector.
Common symptoms
- Rough idle and engine shake
- Hesitation or power loss under load
- Flashing or steady check engine light
- Fuel smell from the exhaust in severe cases
Likely causes
- Worn or fouled spark plug in cylinder 12
- Failing ignition coil on cylinder 12
- Clogged or leaking injector on cylinder 12
- Low compression in cylinder 12
What to check first
- Swap the cylinder 12 coil with a neighbouring cylinder and see if the misfire follows
- Inspect and replace the cylinder 12 spark plug if worn
- Run a compression test on cylinder 12 if ignition and fuel check out
Can you keep driving?
Misfires can quickly overheat the catalytic converter. Keep driving to a minimum and stop if the check engine light flashes.
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All information, explanations and guidance on this page are general preliminary information only. They are estimates and may be entirely wrong, incomplete or inaccurate, or may not apply to your vehicle at all. Never take any action based on this content alone — do not decide to keep driving, clear codes, replace parts, repair or otherwise work on your vehicle based only on what you read here. In every case, and for any final decision, you must consult qualified technical personnel (a professional mechanic, an authorized service centre or an engineer) and obtain their approval before acting. MechanicAI accepts no liability or responsibility whatsoever for any damage, fault, injury, loss or outcome that may arise — directly or indirectly — from using or relying on this information, for any reason and under any circumstances. By using this page you acknowledge and accept these terms.