P0300

DTC P0300
Emission relevant misfire multiple cylinders Drive cycle C:Signal out of range - above maximum.

ALLDATA Editor Note: The Catalyst Damaging Misfire for multiple cylinders is found under code P1300. P1300

Possible causes by suggested order of priority:
- Fuel pressure too low.
- Crank synchronization problem
- Ignition coil fault
- Fuel contamination.
- Engine mechanical fault.

Fuel pressure too low.
- Fuelling adaptations show enrichment.
- Check fuel pressure with fuel pressure gauge.
- Fuel filter blocked.
- Fuel pressure regulator fault.
- Fuel pump fault

Crank synchronization on problem
- Sporadic reference mark error count raised.
- Reset count possibly also raised.
- Crank sensor fault is set.
- Crank sensor wheel physically damaged.
- Crank sensor out of position.
- Crank sensor faulty
- Raised reset count with a zero reference error count may indicate a 12v supply problem.
- Diagnose fault with raised ref error count as a crank sensor fault

Ignition coil fault
- Misfire counts high for all cylinders using coil 2 (1,4,6,7).
- Misfire counts high for all cylinders using coil 1 (2,3,5,8).
- Misfire counts high for all cylinders
- Problem with 12v supply to coil pack 2 (cylinders 1,4,7,6).
- Problem with 12v supply to coil pack 1 (cylinders 2,3,5,8).
- Problem with 12v supply to both coil packs.
- Coil pack 2 faulty
- Raised misfire counts on paired cylinders 4+7, 2+3, 1+6, 5+8 indicate a problem with one coil drive or secondary circuit.
- Raised misfire counts on groups of four cylinders 1+4+6+7 or 2+3+5+8 indicate coil pack problems.
- Raised counts on groups of four cylinders 1+3+5+7 or 2+4+6+8 indicate a bank fuelling problem.

Fuel contamination.
- Misfire counts equally high for all cylinders.
- Fuel pressure measured with fuel pressure gauge reads normal.
- Abnormal fuelling adaptions.
- Visual check of fuel in fuel line (take sample).
- Fuel contaminated.

Engine mechanical fault.
- Raised air flow at idle.
- Cylinder compressions.
- Cylinder leakages.
- Valve timing (CAM).
- Spark plug condition - check for oil or carbon fouling.
- Valve, Piston or CAM problems causing low engine efficiency.
- Engine running rich causing carbon deposits on spark plugs