DTC Troubleshooting
DTC Troubleshooting: P0301, P0302, P0303, P0304, P0305, P0306
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. Reading and Clearing Diagnostic Trouble Codes
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 for 2 minutes (in P or N).
4. Monitor the OBD STATUS for DTC P0301, P0302, P0303, P0304, P0305, or P0306 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, 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
- VSS
- 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 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.
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 the fuel and ignition system circuit connectors for loose wires or poor connections.
9. Turn the ignition switch to LOCK (0).
10. Exchange the ignition coil from the problem cylinder with one from another cylinder.
11. Reconnect all connectors.
12. 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)
- GEAR POSITION
- ECT SENSOR 1
13. 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 14.
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.
14. Determine which cylinder had the misfire.
Does the misfire occur in the cylinder where the ignition coil was moved?
YES - Replace the faulty ignition coil, Service and Repair then go to step 55.
NO - Go to step 15.
15. Turn the ignition switch to LOCK (0).
16. Exchange the spark plug from the problem cylinder with the one from another cylinder.
17. Reconnect all connectors.
18. 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)
- GEAR POSITION
- ECT SENSOR 1
19. 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 20.
NO - Intermittent failure due to spark plug fouling (no misfire at this time).
20. Determine which cylinder had the misfire.
Does the misfire occur in the cylinder where the spark plug was moved?
YES - Replace the faulty spark plug, then go to step 55.
NO - Go to step 21.
21. Turn the ignition switch to LOCK (0).
22. Disconnect the ignition coil 3P connector from the problem cylinder.
23. Turn the ignition switch to ON (II).
24. Measure the voltage between ignition coil 3P connector terminal No. 3 and body ground.
Is there battery voltage?
YES - Go to step 25.
NO - Repair open in the wire between the ignition coil and the ignition coil relay, then go to step 55.
25. Turn the ignition switch to LOCK (0).
26. Check for continuity between ignition coil 3P connector terminal No. 2 and body ground.
Is there continuity?
YES - Go to step 27.
NO - Repair open in the wire between the ignition coil and G101, then go to step 55.
27. Jump the SCS line with the HDS.
28. Disconnect PCM connector A (31P).
29. Check for continuity between body ground and the appropriate PCM connector terminal (see table).
Is there continuity?
YES - Repair short in the wire between the PCM and the ignition coil, then go to step 55.
NO - Go to step 30.
30. Connect appropriate ignition coil 3P connector terminal No. 1 to body ground with a jumper wire (see table).
31. Check for continuity between body ground and the appropriate PCM connector terminal (see table).
Is there continuity?
YES - Go to step 32.
NO - Repair open in the wire between the PCM and the ignition coil, then go to step 55.
32. Turn the ignition switch to ON (II).
33. Measure the voltage between body ground and the appropriate PCM connector terminal (see table).
Is there battery voltage?
YES - Go to step 43.
NO - Go to step 34.
34. Turn the ignition switch to LOCK (0).
35. Remove the intake manifold. Intake Manifold Removal/Installation
36. Disconnect the injector 2P connector from the problem cylinder.
37. Turn the ignition switch to ON (II).
38. Measure the voltage between injector 2P connector terminal No. 1 and body ground.
Is there battery voltage?
YES - Go to step 39.
NO - Repair open in the wire between the injector and PGM-FI main relay 1 (FI MAIN), then go to step 55.
39. Turn the ignition switch to LOCK (0).
40. Check for continuity between body ground and the appropriate PCM connector terminal (see table).
Is there continuity?
YES - Repair short in the wire between the PCM and the injector, then go to step 55.
NO - Go to step 41.
41. Connect appropriate injector 2P connector terminal No. 2 to body ground with a jumper wire (see table).
42. Check for continuity between body ground and the appropriate PCM connector terminal (see table).
Is there continuity?
YES - Go to step 43.
NO - Repair open in the wire between the PCM and the injector, then go to step 55.
43. Measure the resistance between injector 2P connector terminals No. 1 and No. 2.
Is there 10-13 Ohms?
YES - Go to step 44.
NO - Replace the injector, Service and Repair then go to step 55.
44. Exchange the injector from the problem cylinder with the one from another cylinder. Also check the injector fuel inlet screen for debris, and clean it if needed.
45. Reconnect all connectors, and install the intake manifold. Intake Manifold Removal/Installation
46. Turn the ignition switch to ON (II).
47. Clear the DTCs with the HDS.
48. Start the engine, and let it idle without load (in Park or neutral) for 2 minutes.
49. 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)
- GEAR POSITION
- ECT SENSOR 1
50. 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 51.
NO - Intermittent failure due to poor contact in the injector connector (no misfire at this time). Check for poor connections or loose terminals at the injector.
51. Determine which cylinder had the misfire.
Does the misfire occur in the cylinder where the injector was moved?
YES - Replace the faulty injector, Service and Repair then go to step 55.
NO - Go to step 52.
52. Turn the ignition switch to LOCK (0).
53. Do an engine compression and a cylinder leakdown test. Testing and Inspection
Did the engine pass both tests?
YES - Go to step 54.
NO - Repair the engine, then go to step 55.
54. Do the VTEC rocker arm test. VTEC Rocker Arm Test
Did the engine pass the test?
YES - Go to step 63.
NO - Repair the VTEC rocker arm, then go to step 55.
55. Reconnect all connectors.
56. Reset the PCM with the HDS.
57. Clear the CKP pattern with the HDS.
58. Do the PCM idle learn procedure. PCM Idle Learn Procedure
59. Do the CKP pattern learn procedure. Reading and Clearing Diagnostic Trouble Codes
60. 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)
- GEAR POSITION
- ECT SENSOR 1
61. 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 coil, the injector, and the PCM, then go to step 1.
NO - Go to step 62.
62. Monitor the OBD STATUS for DTC P0301, P0302, P0303, P0304, P0305, or P0306 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES - Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 61, go to the indicated DTC's 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 60.
63. Reconnect all connectors.
64. Update the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM. Reading and Clearing Diagnostic Trouble Codes
65. 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)
- GEAR POSITION
- ECT SENSOR 1
66. 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 coil, the injector, and the PCM. If the PCM was updated, substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes then go to step 65. If the PCM was substituted, go to step 1.
NO - Go to step 67.
67. Monitor the OBD STATUS for DTC P0301, P0302, P0303, P0304, P0305, or P0306 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. Service and Repair If any other Pending or Confirmed DTCs were indicated in step 66, go to the indicated DTC's 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, Reading and Clearing Diagnostic Trouble Codes then go to step 65. 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 65.