P0308 Code: Cylinder 8 Misfire Detected
🟠 Moderate severity · drivable
Short drives with a steady light are acceptable, but fix it soon — and stop immediately if the light flashes.
What P0308 means
Cylinder 8 is misfiring, meaning it isn't firing and producing power as it should. As a single-cylinder code, P0308 localizes the fault to cylinder 8's own spark plug, ignition coil, or fuel injector — a much narrower hunt than P0300, the random-misfire code that indicates a shared fuel-delivery or air-intake problem.
Symptoms
- Check engine light on (flashing if severe)
- Rough or shaking idle
- Power loss and hesitation under load
- Worse fuel economy
Common causes
- most common: Worn or fouled spark plug on cylinder 8
- common: Failing ignition coil or plug wire for cylinder 8
- common: Clogged or leaking fuel injector on cylinder 8
- less common: Low compression in cylinder 8 (worn rings, valve, or gasket)
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Swap cylinder 8's plug and coil with a neighboring cylinder to see if the misfire follows the parts | Yes | $0–20 |
| Replace the cylinder 8 spark plug | Yes | $10–50 |
| Replace the cylinder 8 ignition coil | Yes | $50–200 |
| Have cylinder 8 compression-tested | Mechanic | $100–200 |
Frequently asked questions
Is P0308 limited to cylinder 8?
Yes. A single-cylinder misfire means the cause is nearly always that cylinder's spark plug, coil, or injector. If the misfire jumps between cylinders, the code is usually P0300.
What should I check first for P0308?
Do a free swap test: move cylinder 8's spark plug and coil to another cylinder and re-scan. If the misfire moves, replace the moved part. If it stays on 8, suspect the injector or low compression.
Can I drive with a P0308?
Briefly, if the light is steady. A misfire pushes unburned fuel into the catalytic converter, so fix it promptly — and a flashing light means stop and tow immediately.
Related codes
P0300
P0300 Code: Random/Multiple Cylinder Misfire Detected
P0307P0307 Code: Cylinder 7 Misfire Detected
P0301P0301 Code: Cylinder 1 Misfire Detected
Related guide: The 10 Most Common Check Engine Codes →
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.