P0308 — Cylinder 7 Misfire Detected
Drivable short-term, but fix now to avoid damage.
What P0308 means
This code means your engine's computer detected that cylinder 7 is misfiring, meaning it isn't burning the fuel-air mixture completely or at the right time. It's usually caused by worn spark plugs, bad ignition coils, fuel injector problems, or low compression in that cylinder. The fix often starts with replacing spark plugs and coils, and it's a common repair that doesn't always require major engine work.
Common symptoms
- Check engine light is on or flashing
- Rough idle or noticeable engine shaking
- Loss of power during acceleration
- Engine hesitates or stumbles
- Poor fuel economy
Common causes
- Worn or fouled spark plug on cylinder 7
- Faulty ignition coil for cylinder 7
- Clogged or failing fuel injector
- Vacuum leak or low compression in the cylinder
- Damaged spark plug wires or connectors
Typical repair cost
$150 – $1200
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0308 code?
For a very short trip, maybe, but it's risky. A misfire can damage your catalytic converter and worsen quickly, especially if the check engine light is flashing. It's best to get it diagnosed right away.
How much does it cost to fix a P0308 code?
Most repairs run between $150 and $1,200, depending on the cause. A simple spark plug or coil replacement is on the lower end, while injector or compression-related issues cost more.
Is a P0308 code serious?
Yes, it can be. A misfire wastes fuel, hurts performance, and can damage expensive emissions parts if ignored. A flashing check engine light makes it more urgent.
Why only cylinder 7 and not the others?
The code pinpoints cylinder 7 specifically, so the problem is usually local to that cylinder, like its spark plug, coil, or injector. Swapping that coil with a neighboring one can help confirm the source.