P0306: Cylinder 6 Misfire Detected
Severity: high
What it means: The engine computer counted misfires on cylinder 6, meaning that cylinder isn't burning its fuel properly.
Safe to drive? Only briefly, and gently, if the light is steady. Don't drive if the check-engine light is flashing, because unburned fuel can overheat and destroy the catalytic converter.
Common symptoms
- Rough idle or shaking
- Hesitation or loss of power
- Flashing check-engine light under load
- Worse fuel economy
Likely causes, ranked
- Worn spark plug or failing ignition coil on that cylinder$218–$400DIY
CarMD 2024 national averages: ignition coil(s) about $218, coils plus spark plugs about $400
- Fuel injector clogged or not firing$464Shop
CarMD 2024 national average about $464
- Vacuum leak near that cylinderShop
- Low compression (valve, ring or head gasket problem)Shop
What it means: The engine computer counted misfires on cylinder 6, meaning that cylinder isn't burning its fuel properly.
Severity: High. Safe to drive? Only briefly, and gently, if the light is steady. Don't drive if the check-engine light is flashing, because unburned fuel can overheat and destroy the catalytic converter.
DIY or shop?
Swap the coil with a neighboring cylinder to see if the misfire follows it, a common DIY test. Compression and injector testing are shop jobs.
Before you replace parts
- Read all stored codes and freeze-frame data. Fix misfire, fuel or sensor codes before chasing emissions codes.
- Check the simple things first: connectors, vacuum hoses, fluid levels and the gas cap.
- Clear the code only after a repair, then confirm it stays off after a few drives.
- Check your VIN for recalls and service bulletins.
Safety / mechanic note
Verify with a mechanic. This code can involve stalling, engine damage or loss of power. If the check-engine light is flashing, or the car stalls or runs badly, stop driving and have it inspected.