P0304
Cylinder 4 Misfire Detected
High — address promptly / stopPowertrain (engine & transmission)
System
Powertrain (engine & transmission)
Type
Generic (standardized)
Subsystem
Ignition system or misfire
What it means
Cylinder 4 is misfiring — incomplete or absent combustion in that cylinder.
Symptoms
Rough idle, shaking, power loss, possible flashing engine light.
Common causes
Plug/coil on cylinder 4, injector, compression loss or wiring.
Recommended action
Isolate by swapping the coil/plug with an adjacent cylinder; repair without delay.
Related codes
P0300Random/Multiple Cylinder Misfire DetectedP0301Cylinder 1 Misfire DetectedP0302Cylinder 2 Misfire DetectedP0303Cylinder 3 Misfire DetectedP0420Catalyst System Efficiency Below Threshold (Bank 1)P0430Catalyst System Efficiency Below Threshold (Bank 2)P0171System Too Lean (Bank 1)P0174System Too Lean (Bank 2)P0172System Too Rich (Bank 1)P0175System Too Rich (Bank 2)P0101Mass Air Flow (MAF) Circuit Range/PerformanceP0113Intake Air Temperature Sensor Circuit High
FAQ — P0304
What does code P0304 mean?
Cylinder 4 Misfire Detected. Cylinder 4 is misfiring — incomplete or absent combustion in that cylinder.
What are the symptoms of P0304?
Rough idle, shaking, power loss, possible flashing engine light.
What causes P0304?
Plug/coil on cylinder 4, injector, compression loss or wiring.
What should I do about P0304?
Isolate by swapping the coil/plug with an adjacent cylinder; repair without delay.
General reference based on the SAE J2012 standard. Exact causes for your vehicle may differ — when in doubt, consult a workshop.
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