P0308: Cylinder 8 Misfire Detected

What does P0308 mean?

The misfire is on cylinder 8, which is usually the last cylinder on one bank of a V8 and is often at the back of the engine, near the firewall. Heat and limited airflow there can wear out coils and plug wires, and a leaking valve cover gasket can let oil into the plug tube.

Generic OBD-II definition: Cylinder 8 Misfire Detected. Confirm applicability in your vehicle service information.

Common causes

• Spark plug for cylinder 8 worn or fouled
• Coil, boot, or plug wire for cylinder 8 failing
• Injector for cylinder 8 sticking
• Oil in the plug tube from a valve cover gasket leak
• Mechanical wear such as a collapsed lifter or worn cam lobe

Symptoms

• Rough idle and a lopey exhaust note
• Loss of power
• Possible ticking noise if a lifter is involved

Can I keep driving with P0308?

Severity: High Stop or minimize driving and get it looked at right away.

If the check engine light is flashing or the car runs badly, stop driving and have it checked.

Typical fixes

• Inspect the rear plug tube for oil
• Swap cylinder 8's ignition coil with a neighboring cylinder's coil, clear codes, and drive: if the code moves to that cylinder, the coil is bad
• Listen for valve train ticking at idle; a misfire combined with a tick points to a mechanical cause
• Compression-test cylinder 8 if the coil and plug swaps don't move the misfire