DTC Troubleshooting
DTC Troubleshooting: P0301 (71), P0302 (72), P0303 (73), P0304 (74), P0305 (75), P0306 (76)
DTC P0301:
No. 1 Cylinder Misfire Detected
DTC P0302:
No. 2 Cylinder Misfire Detected
DTC P0303:
No. 3 Cylinder Misfire Detected
DTC P0304:
No. 4 Cylinder Misfire Detected
DTC P0305:
No. 5 Cylinder Misfire Detected
DTC P0306:
No. 6 Cylinder Misfire Detected
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information Initial Inspection and Diagnostic Overview.
1. Turn the ignition switch to ON (II).
2. Clear the DTC with the HDS.
3. Start the engine, and let it idle without load (in P or N) for 2 minutes.
4. Monitor the OBD STATUS for DTC P0301, P0302, P0303, P0304, P0305, or P0306 in the DTCs MENU with the HDS.
Does the HDS indicate FAILED?
YES -
Go to step 9.
NO -
If the HDS indicates PASSED, go to step 5. If the HDS indicates EXECUTING, keep idling until a result comes on. If the HDS indicates OUT OF CONDITION or NOT COMPLETED, wait for several minutes, then recheck.
5. Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE show misfire counts?
YES -
Go to step 9.
NO -
Go to step 6.
6. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VEHICLE SPEED
- REL TP SENSOR
- CLV (calculated load value)
- GEAR POSITION
- ECT SENSOR 1
7. Monitor the OBD STATUS for DTC P0301, P0302, P0303, P0304, P0305, or P0306 in the DTCs MENU with the HDS.
Does the HDS indicate FAILED?
YES -
Go to step 9.
NO -
If the HDS indicates PASSED, go to step 8. If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION or NOT COMPLETED, go to step 6.
8. Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE show misfire counts?
YES -
Go to step 9.
NO -
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals in the fuel system and the ignition system.
9. Turn the ignition switch to LOCK (0).
10. Exchange the ignition coil from the problem cylinder with one from another cylinder.
11. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VEHICLE SPEED
- REL TP SENSOR
- CLV (calculated load value)
- GEAR POSITION
- ECT SENSOR 1
12. Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE show misfire counts?
YES -
Go to step 13.
NO -
Intermittent failure due to poor contact at the ignition coil contactor (no misfire at this time). Make sure that the ignition coil connectors are secure.
13. Determine which cylinder had the misfire.
Does the misfire occur in the cylinder where the ignition coil was exchanged?
YES -
Replace the faulty ignition coil, then go to step 38.
NO -
Go to step 14.
14. Turn the ignition switch to LOCK (0).
15. Exchange the spark plug from the problem cylinder with one from the another cylinder.
16. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VEHICLE SPEED
- REL TP SENSOR
- CLV (calculated load value)
- GEAR POSITION
- ECT SENSOR 1
17. Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE show misfire counts?
YES -
Go to step 18.
NO -
Intermittent failure due to spark plug fouling (no misfire at this time).
18. Determine which cylinder had the misfire.
Does the misfire occur in the cylinder where the spark plug was exchanged?
YES -
Replace the faulty spark plug Service and Repair, then go to step 38.
NO -
Go to step 19.
19. Turn the ignition switch to LOCK (0).
20. Exchange the injector from the problem cylinder with one from another cylinder.
21. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VEHICLE SPEED
- REL TP SENSOR
- CLV (calculated load value)
- GEAR POSITION
- ECT SENSOR 1
22. Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE show misfire counts?
YES -
Go to step 23.
NO -
Intermittent failure due to poor contact at the injector connector (no misfire at this time). Check for poor connections or loose terminals at the injector.
23. Determine which cylinder had the misfire.
Does the misfire occur in the cylinder where the injector was exchanged?
YES -
Replace the faulty injector Service and Repair, then go to step 38.
NO -
Go to step 24.
24. Turn the ignition switch to LOCK (0).
25. Do an engine compression test Testing and Inspection.
Did the engine pass the test?
YES -
Go to step 26.
NO -
Repair the engine, then go to step 38.
26. Do the VTEC rocker arm test Rocker Arm and Shaft Inspection.
Did the rocker arm pass the test?
YES -
Go to step 27.
NO -
Repair the VTEC rocker arm, then go to step 38.
27. Turn the ignition switch to LOCK (0).
28. Disconnect the injector 2P connector from the problem cylinder.
29. Turn the ignition switch to ON (II).
30. Measure the voltage between injector 2P connector terminal No. 1 and body ground.
Is there battery voltage?
YES -
Go to step 31.
NO -
Repair an open in the wire between the injector and PGM-FI main relay 1, then go to step 38.
31. Turn the ignition switch to LOCK (0).
32. Jump the SCS line with the HDS.
33. Disconnect PCM connector B (49P).
34. Check for continuity between body ground and the appropriate PCM connector terminal (see table).
Is there continuity?
YES -
Repair a short in the wire between the PCM and the injector, then go to step 39.
NO -
Go to step 35.
35. Connect appropriate injector 2P connector terminal No. 2 to body ground with a jumper wire.
36. Check for continuity between body ground and appropriate PCM connector terminal of the problem cylinder (see table).
Is there continuity?
YES -
Check for poor connections or loose terminals at the injector and PGM-FI main relay 1, then go to step 37.
NO -
Repair an open in the wire between the PCM and the injector, then go to step 38.
37. At the injector side, measure the resistance between injector 2P connector terminals No. 1 and No. 2.
Is there 10-13 Ohms?
YES -
Go to step 47.
NO -
Replace the injector Service and Repair, then go to step 39.
38. Turn the ignition switch to LOCK (0).
39. Reconnect all connectors.
40. Turn the ignition switch to ON (II).
41. Reset the PCM with the HDS.
42. Do the PCM idle learn procedure PCM Idle Learn Procedure.
43. Do the CKP pattern clear/CKP pattern learn procedure.
44. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VEHICLE SPEED
- REL TP SENSOR
- CLV (calculated load value)
- GEAR POSITION
- ECT SENSOR 1
45. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0301, P0302, P0303, P0304, P0305, or P0306 indicated?
YES -
Check for poor connections or loose terminals at the ignition coils, the injectors, and the PCM, then go to the troubleshooting for DTC P0300, P0301, P0302, P0303, P0304, P0305, or P306 DTC Troubleshooting.
NO -
Go to step 46.
46. Monitor the OBD STATUS for DTC P0301, P0302,P0303, P0304, P0305, or P0306 in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?
YES -
Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 50, go to the indicated DTC's troubleshooting.
NO -
If the HDS indicates FAILED, check for poor connections or loose terminals at the ignition coils, the injectors, and the PCM, then go to step 1. If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION or NOT COMPLETED, go to step 44.
47. Reconnect all connectors.
48. Update the PCM if it does not have the latest software PCM Update, or substitute a known-good PCM.
49. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VEHICLE SPEED
- REL TP SENSOR
- CLV (calculated load value)
- GEAR POSITION
- ECT SENSOR 1
50. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0301, P0302, P0303, P0304, P0305, or P0306 indicated?
YES -
Check for poor connections or loose terminals at the ignition coils, the injectors, and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 49. If the PCM was substituted, go to step 1.
NO -
Go to step 51.
51. Monitor the OBD STATUS for DTC P0301, P0302, P0303, P0304, P0305, or P0306 in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?
YES -
If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM Service and Repair. If any other Pending or Confirmed DTCs were indicated in step 55, go to the indicated DTC's troubleshooting.
NO -
If the HDS indicates FAILED, check for poor connections or loose terminals at the ignition coils, the injectors, and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 49. If the PCM was substituted, go to step 1. If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION or NOT COMPLETED, go to step 49.