P0304

Read the instructions below then start the fault diagnostic procedure.

Symptom: Black smoke from exhaust pipe CHECK ENGINE. Loss of performance Misfiring

P0304

Fault symptoms

•	Black smoke from exhaust pipe

•	CHECK ENGINE.

•	Loss of performance

•

Misfiring

On-Board Diagnostics

Type of diagnosis:

-	Continuous.

Enable criteria:

-	Engine running.

-	Battery voltage should be 10.2-15.8 V.

-	Fuel balancing should have been active for 5 seconds.

-	Engine temperature should be over 59 °C.

Fault criteria:

-	No combustion in cylinder 4 for 3s.

Dependents:

-	P0501, P0502, P0503, P0253, P0254, P0258, P0259, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277, P1200, P0200, P0216.

System reaction to a fault:

-

None.

OK report:

-	Fault criteria not fulfilled.

Fault handling: (See section Fault handling III, other emissions-related components and functions for more information)

-

Type III.

Diagnostic help

Functions in the diagnostic tool related to the fault:

-	Read value: Fuel Compensation Cyl. 4

Anything that can cause misfiring can also be the cause of a DTC, such as deviating combustion in a cylinder. This could be caused by; leaking high-pressure fuel lines; damaged pistons (compression), cylinders or valves; mechanical engine fault; faulty injectors; and clogged or leaking high-pressure pipes (refers to conical connection between the nozzles and the fuel rail).

See also description of read value under "Read Values" menu for more information.

Checking the wiring

Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short circuits. Observe the multimeter, diagnostic tool or test lamp during the check.