Cylinder 7 Misfire Detected
The P0307 code means the vehicle's onboard diagnostic system has detected: Cylinder 7 Misfire Detected. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- medium
- Estimated cost
- $8-$30 per spark plug; $30-$80 per coil
The #1 fix for misfire codes. 15-piece set with 14mm, 16mm, 18mm magnetic sockets, T-handle extension, and spark plug gapper.
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Read and clear misfire codes. Shows which cylinder is misfiring so you know exactly what to replace.
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Common Symptoms
- Rough idle on V8 engine
- Check Engine Light on
- Power loss
Probable Causes (Ranked by Likelihood)
- Faulty spark plug on cylinder 7 Very High
- Failed ignition coil on cylinder 7 High
- Clogged fuel injector on cylinder 7 High
- Low compression on cylinder 7 Moderate
Step-by-Step Diagnostic Procedure
-
Swap cylinder 7 coil and spark plug. Confirm whether the misfire follows the component.
-
Injector balance test on cylinder 7.
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Compression test as a final diagnostic step.
Common Fixes by Vehicle
What techs usually find when diagnosing P0307 on specific vehicles — tap your vehicle for the fix and the exact part:
2007-2014 Chevrolet Silverado/GMC Sierra 5.3L/6.0L V8 easy DIY
Cylinder 7 misfire on GM V8s is most often a worn spark plug or a failed ignition coil on that cylinder. Swap the coil from cyl 7 to a neighbor and rescan — if the misfire follows the coil, replace it. Plugs are due every 100K. Rule out a clogged injector or low compression before going deeper.
Labor: 30-60 minFrequently Asked Questions
Where is cylinder 7 on a V8?
On most GM V8 engines (LS family), cylinder 7 is the fourth cylinder on the passenger side (right bank). On Ford V8 engines, cylinder 7 is the third cylinder on the passenger side. Consult your service manual for exact location.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P0307 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
See All Codes & Fixes for Your Vehicle
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