Fault-Code Library · Combustion
P0304: Cylinder 4 misfire detected
The ECU detected repeated combustion misfires on cylinder 4.
Common symptoms
- •Shaking idle
- •Loss of power
- •Flashing warning light
- •Hard starting
Likely causes
- •Coil or plug failure
- •Injector fault
- •Vacuum or intake sealing issue
- •Mechanical compression issue
First checks
- •Review freeze-frame load and RPM
- •Test ignition parts logically
- •Check injector balance and compression if the fault remains
Important
Repeated cylinder-specific misfire should be fixed before catalyst or DPF damage follows.
A fault code identifies a detected condition, not a failed part. Confirm manufacturer-specific subcodes and live data.
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