Common Checks
- Scan for companion cylinder-specific codes and freeze-frame conditions.
- Inspect spark plugs, coils, plug wires on older engines, and coil boots.
- Check for vacuum leaks, fuel pressure problems, and compression issues.
Diagnostic trouble code
P0300 Random/Multiple Cylinder Misfire Detected
The PCM detects misfires that are not isolated to one cylinder.
Misfire CodesCommon Repairs
- Replace worn spark plugs and damaged coil boots or plug wires.
- Swap-test or replace a failed ignition coil.
- Repair vacuum leaks, injector faults, or mechanical compression problems found during testing.
Mustang Notes
- Coil-on-plug modular and Coyote engines often need cylinder-level diagnosis rather than replacing every coil at once.
Model-Year Applicability
Listed for 1996 and newer traditional gasoline Mustang pages in this first-pass catalog. Engine, calibration, and Ford-specific codes may narrow that range as more service data is added.