P0312
Cylinder 12 Misfire Detected
Ignition / misfire
Generic OBD-II
High
What it means
P0312 means the engine computer has detected a misfire on cylinder 12 — fuel isn't burning properly there, so the engine runs rough and loses power. Like other misfire codes it's serious: a sustained misfire can overheat and destroy the catalytic converter, so it's best diagnosed quickly.
High
Can I keep driving? Drive as little as possible, especially if the check-engine light is flashing — an active misfire can quickly overheat and damage the catalytic converter.
Common symptoms
What you'll notice
- Check-engine light on (often flashing during an active misfire)
- Rough idle, shaking, or hesitation, worst at idle or under load
- Reduced power and acceleration
- Poor fuel economy
Common causes
Most likely first
- Worn or fouled spark plug on cylinder 12Likely
- Failing ignition coil on cylinder 12Common
- Clogged or leaking fuel injector on cylinder 12Common
- Low compression on cylinder 12 (valves, rings, head gasket)Less often
- Faulty engine control module (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data to confirm the misfire is on cylinder 12.
- Inspect and replace the cylinder 12 spark plug and coil first — the most common causes.
- Swap the coil or injector with a neighbouring cylinder to see if the misfire follows the part.
- Test injector operation and fuel delivery to cylinder 12.
- If it persists, run a compression test for a mechanical cause. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0312?+
No — especially with a flashing light. A sustained misfire dumps raw fuel into the exhaust and can destroy the catalytic converter.
Can I just clear P0312?+
You can, but it returns within a few drive cycles until the misfire on cylinder 12 is repaired.
Related codes
Often seen with P0312
Read & clear P0312 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX