P0306

P0306

Misfire, Cylinder-Selective

NOTE:
The fault types have special significance for misfires:
- Fault type "Implausible signal": exhaust-related fault after engine startup
- Fault type "Below limit value": exhaust-related during the journey
- Fault type "Above limit value": fault damaging to catalytic converter

NOTE:
- The totals error P0300 is always entered in addition to any other misfires. The misfires may have occurred in one or several cylinders.
- The misfire detection function can block the fuel injection for the remainder of the driving cycle after a permanent misfire is detected on the cylinder in question. Misfire detection remains active.

Diagnostic conditions
- Engine running
- Engine load > 4 to 25% depending on engine speed
- Intake air temperature > -30 degrees C (-22 degrees F)
- No fault in crankshaft sensor
- Testing for misfires while driving: smooth road surface conditions (= no bumpy track)

Possible fault causes
- If a misfire only occurs on one cylinder:
- Electric fault in control line between DME and ignition coil
- Spark plug connector faulty
- Ignition coil faulty
- Spark plug faulty
- Secondary air
- Mechanical or electrical fault in injection valve
- Valve seat or valve faulty
- Valve lift control faulty
- Exhaust system blocked/narrowed
- Foreign bodies in intake tract, this can lead to sporadic misfires on changing cylinders.

When misfires occur on the banks:
- Electric fault or loose contact in the control line to solenoid valve of camshaft adjustment
- Solenoid valve of camshaft adjustment electrically/mechanically faulty or clogged
- Hall sender rotor (sensor wheel) faulty/kinked
- Secondary air
- Intake camshaft adjustment too slow
- Intake camshaft timing incorrect
- Exhaust camshaft timing incorrect
- Fault in the valve lift control
- Oxygen sensor faulty (also: -loose contact in wiring harness)
- Exhaust system blocked/narrowed
- Foreign bodies in intake tract, this can lead to sporadic misfires on changing cylinders.

- When misfires occur on both banks:
- Incorrect/low-grade fuel
- Tank empty
- An engine-block heater is used
- Secondary air
- Exhaust system blocked/narrowed
- Foreign bodies in intake tract, this can lead to sporadic misfires on changing cylinders.