OBD CodesWhat it means
A misfire means a cylinder did not burn its fuel properly on one or more turns. The computer notices because the crankshaft slows for an instant. Codes P0301 to P0312 name the cylinder. P0300 means the misfires move around or affect several cylinders.
Codes in this group
| Code | Meaning |
|---|---|
| P0300 | Misfires on several cylinders, or at random |
| P0301 | Misfire on cylinder 1 |
| P0302 | Misfire on cylinder 2 |
| P0303 | Misfire on cylinder 3 |
| P0304 | Misfire on cylinder 4 |
| P0305 | Misfire on cylinder 5 |
| P0306 | Misfire on cylinder 6 |
| P0307 | Misfire on cylinder 7 |
| P0308 | Misfire on cylinder 8 |
| P0309 | Misfire on cylinder 9 |
| P0310 | Misfire on cylinder 10 |
| P0311 | Misfire on cylinder 11 |
| P0312 | Misfire on cylinder 12 |
| P0313 | Misfire detected with low fuel level |
| P0314 | Misfire on one cylinder (cylinder not identified) |
Bank 1 is the side of the engine that has cylinder 1. Sensor 1 is before the catalytic converter and sensor 2 is after it. More terms explained.
What you may notice
- Engine shaking or stumbling, at idle or under load
- Loss of power
- Check engine light flashing while it happens
- Smell of fuel from the exhaust
Common causes
Most likely first:
- Worn spark plugs
- A failed ignition coil or plug lead
- A blocked or leaking injector
- A vacuum leak
- Low compression from a worn or damaged engine
- Poor or contaminated fuel
What to check first
- If the check engine light is flashing, slow down and avoid hard acceleration: unburnt fuel can destroy the catalytic converter within minutes
- Check when the spark plugs were last changed
- For a single cylinder, a workshop often swaps the coil with a neighbour to see if the misfire moves
Have a mechanic confirm. A fault code tells you which system reported a problem, not which part has failed. The same code can have several causes, and they differ between car models. Use this page to understand the code, then have a qualified mechanic test the car before any part is replaced.
After the repair
Once the cause is fixed, the code can be cleared with a scan tool, or the warning light goes out by itself after several trips without the fault. Clearing a code without fixing the cause only hides it for a while. More about clearing codes.
Related codes
Crankshaft and camshaft timing do not agree (P0016), Knock sensor (P0325), Crankshaft position sensor (P0335), Camshaft position sensor (P0340), Ignition coil circuits (P0350), Glow plugs (diesel) (P0380). All codes.
Written in November 2026. These are generic OBD-II codes, the same on all makes. Causes and repair steps differ between models.