P0302 – Cylinder 2 Misfire Detected
What does P0302 mean?
The engine computer has detected a misfire in cylinder 2 specifically. Because the fault is isolated to one cylinder rather than random, diagnosis is direct: the cause is almost always the spark plug, ignition coil, fuel injector, or compression in that single cylinder.
What causes P0302?
Listed from most to least common:
- 1Worn or fouled spark plug in cylinder 2
- 2Failing ignition coil on cylinder 2
- 3Clogged or failed fuel injector on cylinder 2
- 4Damaged spark plug wire on vehicles that use them
- 5Vacuum leak at cylinder 2's intake runner
- 6Low compression from a burnt valve, worn rings, or head gasket failure
Code breakdown
Common symptoms
- Check engine light on or flashing
- Rough idle with a distinct stumble
- Vibration felt through the vehicle, worst at idle
- Hesitation and power loss on acceleration
- Increased fuel consumption
How to diagnose
- 1Identify which physical cylinder is number 2 on your engine — numbering differs between inline, V, and boxer layouts, and guessing wastes money.
- 2Remove and inspect the cylinder 2 spark plug, comparing it against plugs from other cylinders.
- 3Swap the cylinder 2 ignition coil with an adjacent cylinder, clear codes, and drive. If the code becomes P0301 or P0303, the coil is confirmed faulty.
- 4Swap the injector the same way to test it.
- 5Run a compression test on cylinder 2. Low compression means the problem is mechanical, not ignition or fuel.
- 6If compression is low, follow with a leak-down test to determine whether it is rings, valves, or head gasket.
Raw fuel from a misfiring cylinder can overheat and destroy the catalytic converter. If the check engine light is flashing, stop driving and have the vehicle towed.
Common fixes and estimated costs
| Repair | Estimated cost |
|---|---|
| Replace spark plugs (full set recommended) | $100–$350 |
| Replace ignition coil | $100–$350 |
| Replace fuel injector | $150–$500 |
| Head gasket or valve repair | $1,200–$3,000 |
Costs are rough US estimates including parts and labor. Actual pricing varies significantly by vehicle, region, and shop rates.
Good to know
The coil-swap test costs nothing and gives a definitive answer within one drive cycle. On transverse-mounted V6 engines, rear-bank cylinders are significantly harder to reach, which raises labor cost — worth knowing before getting a quote.
Related codes
This information is provided for general reference only and may vary by manufacturer, model, and year. It is not a substitute for professional diagnosis or repair.