P0301
DTC P0301: No.1 Cylinder MisfireDTC P0302: No.2 Cylinder Misfire
DTC P0303: No.3 Cylinder Misfire
DTC P0304: No.4 Cylinder Misfire
NOTE: If some of the DTCs listed below are stored at the some time as a misfire DTC, troubleshoot those DTCs first, then recheck for the misfire DTC.
P0131, P0132: Primary HO(2)S
P0171, P0172: Fuel Supply System
P0401: EGR System
P1359, P1361, P1362: TDC Sensor
P1381, P1382: CYP Sensor
1. Start the engine, listen for a clicking sound from the injector in the problem cylinder.
Does it click?
YES - Go to step 2.
NO - Go to step 11.
2. After checking and recording the freeze data, do the ECM/PCM Reset Procedure. If there is no freeze data of misfiring, just clear the DTC.
3. Exchange the spark plug from the problem cylinder with one from another cylinder.
4. Test-drive the vehicle several times in the range of the freeze data or under various conditions if there was no freeze data.
5. Check for a DTC or Temporary DTC with the scan tool.
Is DTC P0301, P0302, P0303, P0304, or Temporary DTC P1399 indicated?
YES - Go to step 6.
NO - Intermittent misfire due to spark plug fouling, etc. (no misfire at this time).
6. Determine which cylinder(s) had the misfire. Does the misfire occur in the cylinder where the spark plug was exchanged?
YES - Replace the faulty spark plug.
NO - Go to step 7.
7. Exchange the injector from the problem cylinder with one from another cylinder.
8. Let the engine idle for 2 minutes.
9. Test-drive the vehicle several times in the range of the freeze data or under various conditions if there was no freeze data.
Is DTC P0301, P0302, P0303, P0304, or Temporary DTC P1399 indicated?
YES - Go to step 10.
NO - Intermittent misfire due to bad contact in the injector connector (no misfire at this time).
10. Determine which cylinder(s) had the misfire.
Does the misfire occur in the cylinder where the injector was exchanged?
YES - Replace the faulty injector.
NO - Check the engine compression, and perform a cylinder leak down test.
11. Check for an open or short in the harness between the ECM/PCM and the injector.
Are the wires OK?
YES - Go to step 12.
NO - Repair open or short in the wire.
12. Install a known-good injector, and recheck. Does the injector click?
YES - Replace the injector.
NO - Substitute a known-good ECM/PCM and recheck. If the symptom/indication goes away, replace the original ECM/PCM.