P0301 GMC Sierra 1500
Cylinder 1 Misfire Detected · Powertrain Code · High · Repair: Easy
What is P0301?
Misfire detected in cylinder 1. Typically caused by a worn spark plug, bad ignition coil, faulty fuel injector, or low compression in that cylinder.
When the GMC Sierra 1500 triggers code P0301 (cylinder 1 misfire detected), it typically points to an issue in the powertrain system. This is a high severity code, so address it promptly to avoid further damage or safety concerns. Below you'll find the most common causes, symptoms, and repair options specific to the GMC Sierra 1500.
This repair is rated easy, meaning basic tools, no lift needed.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your GMC Sierra 1500.
Common Causes on GMC Sierra 1500
- Ignition coil failure on cylinder 1 coil-on-plug on 5.3L or 6.2L V8
- AFM (Active Fuel Management) lifter collapse on cylinder 1
- Worn spark plug with excessive gap on high-mileage V8
- Fuel injector clogged or electrically failed on cylinder 1
- Low compression from valve seat recession or head gasket leak
Symptoms
- Rough idle with noticeable engine vibration
- Engine shaking or vibration especially at idle
- Loss of power during acceleration
- Check engine light flashing (indicating catalytic converter damage risk)
- Poor fuel economy from unburned fuel
- Unburned fuel smell from exhaust
Notes for GMC Sierra 1500
Swap coil from cylinder 1 to another cylinder to see if misfire follows; confirms coil vs other cause.