P0303 Ford F-150
Cylinder 3 Misfire Detected · Powertrain Code · High · Repair: Moderate
What is P0303?
Misfire detected in cylinder 3. Typically caused by a worn spark plug, bad ignition coil, faulty fuel injector, or low compression in that cylinder.
When the Ford F-150 triggers code P0303 (cylinder 3 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 Ford F-150.
This repair is rated moderate, meaning some experience and specialty tools required.
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 Ford F-150.
Common Causes on Ford F-150
- Failed coil-on-plug ignition coil on cylinder 3
- Worn or fouled spark plug on cylinder 3
- Intake valve carbon deposits (EcoBoost direct injection)
- Low compression on cylinder 3 from valve or piston ring issue
Symptoms
- Check engine light (flashing if active misfire)
- Rough idle
- Vibration felt through steering wheel
- Reduced power under acceleration
- Increased exhaust emissions
Notes for Ford F-150
On EcoBoost engines, if multiple cylinders start misfiring at 60k+ miles, carbon buildup on intake valves is likely — a walnut blast service resolves it.