TORQDEX // POWERTRAIN DTC
Cylinder 4 Misfire Detected
Misfire activity has been detected repeatedly on cylinder 4.
00 // CODE DEFINITION
What P0304 means
P0304 identifies abnormal combustion events associated with cylinder 4.
Ignition components, fuel delivery, compression, wiring, or localized intake problems should be investigated.
01 // COMMON SYMPTOMS
What you may notice
02 // COMMON CAUSES
What can trigger P0304?
Ignition problem
Plug, coil, wire, or connection faults may affect cylinder 4.
Fuel delivery problem
The cylinder 4 injector may be restricted or electrically faulty.
Compression problem
Valve, piston, ring, gasket, or valvetrain faults may cause low compression.
03 // DRIVEABILITY
Can I keep driving with P0304?
Driving may be possible if the misfire is mild, but avoid continued driving if the check-engine light is flashing, the engine is shaking heavily, or power is significantly reduced. An active misfire can damage the catalytic converter.
04 // DIAGNOSTIC ORDER
Start here
Confirm the misfire
Review scan-tool data to verify cylinder 4 activity.
Inspect ignition
Check the spark plug and coil or other ignition components.
Evaluate fuel delivery
Test injector operation and electrical control.
Verify compression
Compare cylinder 4 compression with the other cylinders.
05 // COMMON REPAIR AREAS
Systems commonly involved
These are common areas associated with P0304. Testing should confirm the actual fault before parts are replaced.
Ignition problem
Plug, coil, wire, or connection faults may affect cylinder 4.
Fuel delivery problem
The cylinder 4 injector may be restricted or electrically faulty.
Compression problem
Valve, piston, ring, gasket, or valvetrain faults may cause low compression.
06 // DIAGNOSTIC PRINCIPLE
Confirm the fault before replacing parts
P0304 identifies a condition detected by the vehicle control system. It does not automatically identify one failed component. Test the affected system before replacing parts.
07 // RELATED TORQDEX DIAGNOSTICS
Related diagnostic guides
Continue troubleshooting by symptom and system. These TorqDex guides cover common diagnostic paths associated with this trouble code.
08 // RELATED CODES