P0302
Cylinder 2 Misfire Detected.
- Generic
- Powertrain
- Generic code
- High severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 3
- AreaIgnition system or misfire
- 02
- FaultThe specific fault in that area
What it means
P0302 means the engine control unit has detected a misfire on cylinder 2. It sets this when crankshaft speed signals show cylinder 2 is not contributing its share of power, either randomly or repeatedly. The code only says which cylinder is affected, not why it is misfiring, so the cause must be found by testing ignition, fuel, air and mechanical condition on that cylinder.
Symptoms
- Rough or uneven idle
- Engine shaking or juddering, especially under load
- Hesitation or loss of power on acceleration
- Flashing or constant engine warning light
- Smell of unburnt fuel or a noticeably worse fuel economy
- Difficult starting or occasional stalling
Possible causes
- Worn or fouled spark plug on cylinder 2likely
- Faulty ignition coil or coil connector on cylinder 2likely
- Faulty or clogged fuel injector on cylinder 2, or its wiringpossible
- Vacuum or intake leak near cylinder 2 (split hose, leaking intake gasket)possible
- Low compression on cylinder 2 (valve, piston ring or head gasket problem)possible
- Carbon build-up or a sticking EGR valve causing poor mixture on that cylinder (depends on engine)rare
- Wiring or connector fault on the ignition or injector circuit for cylinder 2rare
How to diagnose
- Read all stored and pending codes and note the freeze frame data (load, engine speed, coolant temperature) to see when the misfire occurs.
- Check whether other cylinders are also reporting misfires, as that points towards a common cause such as fuel supply, air leaks or a sensor fault.
- Visually inspect the cylinder 2 coil, connector, wiring and spark plug for damage, oil, moisture or heavy wear.
- Swap the cylinder 2 coil with another cylinder and clear the codes; see if the misfire follows the coil. Repeat with the spark plug if needed.
- Check for intake leaks by inspecting hoses and gaskets, and look at live fuel trim data for signs of a lean condition.
- Test the cylinder 2 injector for correct resistance and operation, and check its supply and control signals.
- Carry out a compression test or cylinder leakage test on cylinder 2 if ignition and fuel checks are clear.
- Check manufacturer information for the specific engine, as known faults and test procedures vary by model.
How to fix
- Replace the worn spark plug on cylinder 2, and normally the full set if they are due for service.
- Replace the faulty ignition coil, or repair its connector or wiring.
- Clean or replace the faulty fuel injector on cylinder 2, or repair its wiring.
- Repair intake leaks by replacing split hoses or leaking gaskets.
- Repair the mechanical fault found on cylinder 2, such as valve, piston ring or head gasket repair.
- Clean carbon deposits or repair a faulty EGR valve if testing shows it is affecting that cylinder.
Can I keep driving?
High severity
Limit driving, and stop at once if the warning light is flashing, as a misfire can overheat and damage the catalytic converter. If the light is steady and the engine runs reasonably, drive gently and get it checked as soon as possible.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.