P0304

TORQDEX // POWERTRAIN DTC

Cylinder 4 Misfire Detected

Misfire activity has been detected repeatedly on cylinder 4.

CODE FAMILY Powertrain
SEVERITY HIGH
DRIVEABILITY May Be Limited
COMMON AREA Cylinder 4 / Ignition / Fuel / Mechanical

01 // 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.

02 // COMMON SYMPTOMS

What you may notice

Rough idle
Engine shaking
Hesitation
Reduced power
Flashing check-engine light

03 // COMMON CAUSES

What can trigger P0304?

IGNITION

Ignition problem

Plug, coil, wire, or connection faults may affect cylinder 4.

FUEL

Fuel delivery problem

The cylinder 4 injector may be restricted or electrically faulty.

MECHANICAL

Compression problem

Valve, piston, ring, gasket, or valvetrain faults may cause low compression.

04 // DIAGNOSTIC ORDER

Start here

01

Confirm the misfire

Review scan-tool data to verify cylinder 4 activity.

02

Inspect ignition

Check the spark plug and coil or other ignition components.

03

Evaluate fuel delivery

Test injector operation and electrical control.

04

Verify compression

Compare cylinder 4 compression with the other cylinders.

05 // 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.