Generic fault code
P0312 — Cylinder 12: misfire detected
The control unit stores code P0312 when it detects this fault: “Cylinder 12: misfire detected”.
Indicative severity: HighIgnition and misfire
Reviewed by Daniel Morales, founder of Reprorace SL, on
What does code P0312 mean?
Spark plugs and coils make the spark that burns the mixture in each cylinder. If a cylinder does not fire properly, the engine shakes and loses power, and unburnt fuel can damage the catalytic converter.
- System
- P · Powertrain
- Area
- Ignition and misfire · Car system: Ignition
- Type
- Generic (SAE J2012 / ISO 15031-6): the same meaning on every make
- Indicative severity
- High. Diagnose as soon as possible: it may affect safety or cause damage (engine, catalyst, brakes).
What usually causes code P0312?
- Ignition system fault (spark plug, coil, lead)
The most likely causes come first. Only a check on the car confirms which one is yours.
What are the symptoms of code P0312?
- The engine shakes or stumbles, especially at idle or when accelerating
- Loss of power and jerking
- A flashing engine light if the misfires are severe
These are the usual symptoms of this kind of fault: not all of them always appear, and sometimes you notice nothing.
Can I keep driving with code P0312?
Better not, except when you really have to. This fault may affect safety or damage the engine, the catalytic converter or the brakes. See a workshop as soon as possible; if you must move the car, drive gently and only short distances. If the light flashes, the car loses power, makes unusual noises or the brakes or steering feel different, stop somewhere safe and call for assistance.
This is guidance only: only someone who checks the car can say whether it is safe to drive.
An indicative description of the code's generic meaning. Each manufacturer may give it a different meaning, conditions or tests: always follow its service information and your workshop's advice.
What you can do yourself
For this kind of fault
If the light flashes, drive gently to the workshop without flooring the pedal: unburnt fuel can overheat the catalytic converter and damage it. Note which cylinder the code names; workshops usually start with that cylinder's spark plug, coil and injector.
Read the code and keep the report: with an ECO-LITE in the OBD socket you see it on your phone or computer, with the data captured when the fault happened.
Look for anything obvious: a loose connector, a disconnected hose, a fuel cap not closed properly or a low fluid level. Do not take apart anything you do not know.
Clear the code only after writing it down or after the repair. Clearing turns the light off, but it also deletes the freeze-frame data and the readiness monitors used at the inspection.
Drive normally for a few days and read the codes again. If the code comes back, the fault is still there: book the workshop and bring the report.
Read your car's fault codes on your phone
With an ECO-LITE in the OBD socket you see the codes in your account, with the data captured when the fault happened, and your workshop can check them remotely, always with your permission.
Related codes
- P0309Cylinder 9: misfire detected
- P0310Cylinder 10: misfire detected
- P0311Cylinder 11: misfire detected
- P0313Misfire detected with low fuel level
- P0314Single-cylinder misfire (cylinder not specified)
- P0316Misfire detected at start-up (first 1000 revolutions)
P03xx codes: ignition system or misfire
In the glossary
Read more: Remote OBD diagnostics: what it is, how it works and what it can't do