DTC Troubleshooting
DTC P0301: No. 1 Cylinder Misfire DetectedDTC P0302: No. 2 Cylinder Misfire Detected
DTC P0303: No. 3 Cylinder Misfire Detected
DTC P0304: No. 4 Cylinder Misfire Detected
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.
1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Start the engine, and let it idle without load (in Park or neutral).
4. Monitor the OBD STATUS for DTC P0301, P0302, P0303, or P0304 in the DTCs MENU with the HDS.
Does the screen indicate FAILED?
YES - Go to step 9.
NO - If the screen indicates PASSED, go to step 5. If the screen indicates EXECUTING, keep idling until a result comes on. If the screen indicates OUT OF CONDITION, wait for several minutes, and recheck.
5. Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 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
- VSS
- REL TP SENSOR
- CLV (calculated load value)
- APP SENSOR
7. Monitor the OBD STATUS for DTC P0301, P0302, P0303, or P0304 in the DTCs MENU with the HDS.
Does the screen indicate FAILED?
YES - Go to step 9.
NO - If the screen indicates PASSED, go to step 8. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 6 and recheck.
8. Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE show misfire counts?
YES - Go to step 9.
NO - Intermittent failure, the system is OK at this time. Check the fuel system circuit connectors for loose wires or poor connections.
9. Turn the ignition switch OFF.
10. Exchange the ignition coils from the problem cylinder with those from another cylinder.
11. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VSS
- REL TP SENSOR
- CLV (calculated load value)
- APP SENSOR
12. Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE show misfire counts?
YES - Go to step 13.
NO - Intermittent misfire due to poor contact at the ignition coil connector (no misfire at this time). Make sure the coil connections are secure.
13. Determine which cylinder had the misfire.
Does the misfire occur in the cylinder where the ignition coils were exchanged?
YES - Replace the faulty ignition coil, then go to step 49.
NO - Go to step 14.
14. Turn the ignition switch OFF.
15. Exchange the spark plugs from the problem cylinder with those from another cylinder.
16. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VSS
- REL TP SENSOR
- CLV (calculated load value)
- APP SENSOR
17. Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE show misfire counts?
YES - Go to step 18.
NO - Intermittent misfire 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 plugs were exchanged?
YES - Replace the faulty spark plug, then go to step 49.
NO - Go to step 19.
19. Turn the ignition switch OFF.
20. Exchange the injector from the problem cylinder with one from the another cylinder.
21. Start the engine, and let it idle for 2 minutes.
22. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VSS
- REL TP SENSOR
- CLV (calculated load value)
- APP SENSOR
23. Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE show misfire counts?
YES - Go to step 24.
NO - Intermittent misfire due to bad contact in the injector connector (no misfire at this time). Check for poor connections or loose terminals at the injector.
24. Determine which cylinder had the misfire.
Does the misfire occur in the cylinder where the injector was exchanged?
YES - Replace the faulty injector, then go to step 49.
NO - Go to step 25.
25. Turn the ignition switch OFF.
26. Disconnect the ignition coil 3P connectors from the problem cylinder.
27. Turn the ignition switch ON (II).
28. Measure voltage between ignition coil 3P connector terminal No. 3 and body ground.
Is there battery voltage?
YES - Go to step 29.
NO - Repair open in the wire between the ignition coil and the No. 14 IGNITION COIL (IN) (15 A) fuse (or No. 13 IGNITION COIL (EX) (15 A) fuse)*, then go to step 47.
*: exhaust side
29. Turn the ignition switch OFF.
30. Check for continuity between ignition coil 3P connector terminal No. 2 and body ground.
Is there continuity?
YES - Go to step 31.
NO - Repair open in the wire between the ignition coil and G102, then go to step 47.
31. Jump the SCS line with the HDS.
32. Disconnect PCM connector C (44P).
33. Check for continuity between body ground and the appropriate PCM connector terminal of the problem cylinder (see table).
Is there continuity?
YES - Repair short in the wire between the PCM and the ignition coil, then go to step 47.
NO - Go to step 34.
34. Check for continuity between appropriate ignition coil 3P connector terminal No. 1 and the appropriate PCM connector terminal of the problem cylinder (see table).
Is there continuity?
YES - Go to step 35.
NO - Repair open in the wire between the PCM and the ignition coil, then go to step 47.
35. Do an engine compression and a cylinder leakdown test.
Did the engine pass both tests?
YES - Go to step 36.
NO - Repair the engine, then go to step 47.
36. Do the VTEC rocker arm test.
Did the engine pass the test?
YES - Go to step 37.
NO - Repair the VTEC rocker arm, then go to step 47.
37. Turn the ignition switch ON (II).
38. Measure voltage between body ground and the appropriate PCM connector terminal of the problem cylinder (see table).
Is there battery voltage?
YES - Go to step 46.
NO - Go to step 39.
39. Turn the ignition switch OFF.
40. Disconnect the injector 2P connector from the problem cylinder.
41. Turn the ignition switch ON (II).
42. Measure voltage between injector 2P connector terminal No. 1 and body ground.
Is there battery voltage?
YES - Go to step 43.
NO - Repair open in the wire between the injector and PGM-FI main relay 1, then go to step 47.
43. Turn the ignition switch OFF.
44. Check for continuity between body ground and the appropriate PCM connector terminal of the problem cylinder (see table).
Is there continuity?
YES - Repair short in the wire between the PCM and the injector, then go to step 47.
NO - Go to step 45.
45. Check for continuity between appropriate injector 2P connector terminal No. 2 and the appropriate PCM connector terminal of the problem cylinder (see table).
Is there continuity?
YES - Go to step 46.
NO - Repair open in the wire between the PCM and the injector, then go to step 47.
46. At the injector side, measure resistance between injector 2P connector terminals No. 1 and No. 2.
Is there 10 - 13 ohms?
YES - Go to step 57.
NO - Replace the injector, then go to step 47.
47. Turn the ignition switch OFF.
48. Reconnect all connectors.
49. Turn the ignition switch ON (II).
50. Reset the PCM with the HDS.
51. Clear the CKP pattern with the HDS.
52. Do the PCM idle learn procedure.
53. Do the CKP pattern learn procedure.
54. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VSS
- REL TP SENSOR
- CLV (calculated load value)
- APP SENSOR
55. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0301, P0302, P0303, or P0304 indicated?
YES - Check for poor connections or loose terminals at the ignition coil, the injector, and the PCM, then go to troubleshooting DTC P0300, P0301, P0302, P0303, or P0304.
NO - Go to step 56.
56. Monitor the OBD STATUS for DTC P0301, P0302, P0303, or P0304 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 55, go to the indicated DTCs troubleshooting.
NO - If the screen indicates FAILED, check for poor connections or loose terminals at the ignition coil, the injector, and the PCM, then go to step 1. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 54.
57. Reconnect all connectors.
58. Update the PCM if it does not have the latest software, or substitute a known-good PCM.
59. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VSS
- REL TP SENSOR
- CLV (calculated load value)
- APP SENSOR
60. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0301, P0302, P0303, or P0304 indicated?
YES - Check for poor connections or loose terminals at the ignition coil, the injector, and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 59. If the PCM was substituted, go to step 1.
NO - Go to step 61.
61. Monitor the OBD STATUS for DTC P0301, P0302, P0303, or P0304 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM. If any other Temporary DTCs or DTCs were indicated in step 60, go to the indicated DTCs troubleshooting.
NO - If the screen indicates FAILED, check for poor connections or loose terminals at the ignition coil, the injector, and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 59. If the PCM was substituted, go to step 1. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 59.