PACCAR MX (2004 Emissions) Fault Code: P1303 Cylinder 3 – Intermittent Misfire

PACCAR MX (2004 Emissions) Fault Code: P1303 Cylinder 3 – Intermittent Misfire

SET CONDITIONS:
This DTC is set when the PCI ECU (D420) detects more than 20 misfires on cylinder 3, within 1000 crankshaft rotations.

DIAGNOSTIC CONDITION:
This diagnostic runs continuously when the following is true:
1. The coolant temperature is greater than 10?C [50?F] and
2. The engine load is stable and
3. When the engine speed is between 900 and 1650 rpm and
4. No DTCs are present related to fuel pressure, fuel injectors, camshaft, crankshaft, oil and coolant temperature.
5. The amount of injected fuel is between 70 and 220 mg/stroke.

CORRESPONDING OBD READINESS MONITOR:
Misfire monitor

RESET CONDITION:
This DTC will change to inactive after the ignition is keyed OFF and ON again and the diagnostic runs and passes.

REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the following conditions:
– Corresponding readiness monitor displays ‘Ready’
– Diagnostic conditions are met
– Set conditions are met
3. Did the DTC come back? (Can be pending, inactive or active)
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
1. Malfunction in the EGR circuit
2. Malfunction in the fuel injection circuit

ADDITIONAL INFORMATION:
This DTC is typically the result of a malfunction in another system or component. If related DTCs are present, troubleshoot these first.