P0308: Cylinder 8 Misfire Detected
The engine computer saw cylinder 8 slow the crankshaft down, meaning that cylinder isn't firing properly. Because it's one cylinder, the cause is usually a part that serves only that cylinder.
Green, yellow, red: three ways P0308 can look
The same code can be a quick fix or a reason to pull over. Match your situation to the closest example.
Keep an eye on it
A cylinder 8 misfire count shows up once on a cold, wet morning and the engine runs smooth after warm-up.
Schedule a repair
The miss is steady and you can feel it at idle. Schedule a repair. It's often a coil or plug, a fairly simple fix if done before the catalytic converter is damaged.
Stop and get help
Flashing check engine light or heavy shaking. Stop driving soon. Raw fuel from a dead cylinder can overheat the catalytic converter or wash down the cylinder.
Symptoms you might notice
- Rough idle or a steady shake
- Loss of power
- Check engine light, possibly flashing
Common causes, cheapest first
- Worn or fouled spark plug in cylinder 8
- Failing ignition coil on cylinder 8
- Clogged or leaking fuel injector on cylinder 8
- Vacuum leak near that cylinder's intake runner
- Low compression from a valve or head gasket problem
What you can check before calling
- Ask a shop to swap the cylinder 8 coil with a neighbor and see if the misfire follows it
- Look for oil in the spark plug well, a sign of a leaking valve cover gasket
- Check when the plugs were last replaced
A code points to a system, not a part. Replacing parts based on the code alone is how people spend money without fixing the problem. Testing confirms the cause first.
Want the full story? Read our guide: P0300–P0308 misfire codes, explained.
Generic codes (second character 0) mean the same thing on every vehicle. Some manufacturers add their own details, so check service information for your exact vehicle.
Related codes
More misfire & ignition codes
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does P0308 mean?
P0308 means "Cylinder 8 Misfire Detected". The engine computer saw cylinder 8 slow the crankshaft down, meaning that cylinder isn't firing properly. Because it's one cylinder, the cause is usually a part that serves only that cylinder.
Can I drive with code P0308?
It depends on what the vehicle is doing. Green: A cylinder 8 misfire count shows up once on a cold, wet morning and the engine runs smooth after warm-up. Yellow: The miss is steady and you can feel it at idle. Schedule a repair. It's often a coil or plug, a fairly simple fix if done before the catalytic converter is damaged. Red: Flashing check engine light or heavy shaking. Stop driving soon. Raw fuel from a dead cylinder can overheat the catalytic converter or wash down the cylinder.
What causes P0308?
The most common causes are: worn or fouled spark plug in cylinder 8; failing ignition coil on cylinder 8; clogged or leaking fuel injector on cylinder 8.
Is P0308 a serious code?
It can be. Flashing check engine light or heavy shaking. Stop driving soon. Raw fuel from a dead cylinder can overheat the catalytic converter or wash down the cylinder.
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