P0307: Cylinder 7 Misfire Detected
Severity: high
What it means: The engine computer has detected that cylinder 7 is misfiring, meaning it isn't burning fuel properly.
Safe to drive? Not if the check-engine light is flashing. A heavy misfire can overheat and damage the catalytic converter.
Common symptoms
- Check-engine light (may flash)
- Shaking or rough idle
- Loss of power
- Ticking from the top of the engine (on lifter failures)
Likely causes, ranked
- Spark plug or ignition coilDIY
- Fuel injectorShop
- Collapsed lifter or worn camshaft (on GM AFM V8s)Shop
- Vacuum leak or low compressionShop
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Vehicle-specific notes
- 2015–2020 Chevrolet Suburban: 5.3L AFM lifter failure; GM bulletin replaces lifters and guides and checks the camshaft. Read the full answer · Source
- 2015–2020 GMC Yukon: Same 5.3L AFM lifter problem as the Suburban. Read the full answer · Source
What it means: The engine computer has detected that cylinder 7 is misfiring, meaning it isn't burning fuel properly.
Severity: High. Safe to drive? Not if the check-engine light is flashing. A heavy misfire can overheat and damage the catalytic converter.
DIY or shop?
Plug and coil swaps are DIY. Lifter and cam work is a shop job.
Before you replace parts
- Swap the cylinder 7 coil with another cylinder and see if the misfire moves.
- Check the spark plug.
- If plugs and coils are fine, have a shop check the injector, compression and lifters.
- Check your VIN for recalls and bulletins.
Safety / mechanic note
Verify with a mechanic. A flashing check-engine light means stop driving. A code points to a circuit or system, not always a specific part.
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