P0302: Cylinder 2 is misfiring
Cylinder 2 Misfire Detected
If the light is flashing, stop and get towed. Raw fuel is entering the exhaust and destroying your catalytic converter. If the light is steady and the idle is smooth, drive gently to a shop today.
What it means
P0302 means cylinder 2 fired without producing a complete combustion event often enough for the PCM to log it as a problem. Every misfire on cylinder 2 sends unburned fuel into the exhaust. A small amount of that passes through the catalytic converter and combusts there at extreme temperatures. Enough misfires overheat and melt the converter's honeycomb structure. That is why a flashing light is urgent. The misfire also means the engine is effectively down one cylinder, which you will feel as vibration and lost power.
Common causes
- Failed ignition coil on cylinder 2Coils fail on their own schedule. Swapping the coil to another cylinder and seeing if the code moves is the fastest confirmation.
- Worn or fouled spark plug on cylinder 2Check mileage. A plug past its service life is the simplest and cheapest fix.
- Clogged or leaking fuel injector on cylinder 2A clogged injector starves the cylinder. A leaking one floods it. Both misfire.
- Compression loss on cylinder 2Worn rings, burned valve, or head gasket leak. A compression test will confirm.
- Vacuum or intake leak near cylinder 2Extra air leans out the mixture to the point the cylinder will not ignite reliably.
What it costs
- Spark plug replacement (set)$80 to $250
- Ignition coil replacement (one)$150 to $400 installed
- Fuel injector replacement (one)$150 to $400 installed
- Compression repair (head gasket or valves)$900 to $3,500 depending on severity
Symptoms
- Check engine light on, flashing or steady
- Rough idle and vibration, especially at a stop
- Hesitation when accelerating
- Reduced power
- Possible fuel smell from the exhaust
What to do next
Start by swapping the cylinder 2 coil with an adjacent cylinder. If the misfire moves to the new cylinder, replace the coil. If it stays on cylinder 2, swap the spark plug next. If both are fine, have the injector tested and run a compression check. Do not throw parts at it without testing first. A coil swap costs nothing and takes five minutes.
Lewis shows cylinder 2 misfire counts per 1,000 engine revolutions alongside ignition timing and fuel trim data, so you can see the pattern before replacing anything. Download Lewis.
Related codes
FAQ
- How do I confirm the coil is bad?
- Swap the cylinder 2 coil with another cylinder's coil. If the misfire follows the coil to the new cylinder, the coil is bad. If the misfire stays on cylinder 2, the coil is fine.
- Can bad gas cause P0302?
- Contaminated or water-diluted fuel can cause a misfire. If all cylinders misfire after a fill-up, bad fuel is likely. A single-cylinder misfire is more likely ignition or mechanical.
- Will the car fail emissions with P0302?
- Yes. Any misfire code causes an automatic emissions test failure.