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. Initial Inspection and Diagnostic Overview
1. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
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), or press the engine start/stop button to select the OFF mode.
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
- VSS
- 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 moved?
YES - Replace the faulty ignition coil, Service and Repair then go to step 44.
NO - Go to step 14.
14. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
15. Exchange the spark plug from the problem cylinder with the one 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)
- 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 moved?
YES - Replace the faulty spark plug, then go to step 44.
NO - Go to step 19.
19. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
20. Jump the SCS line with the HDS.
21. Disconnect PCM connector B (49P).
22. Remove the intake manifold. Intake Manifold Removal and Installation
23. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
24. Measure the voltage between body ground and the appropriate PCM connector terminal (see table).
Is there battery voltage?
YES - Go to step 32.
NO - Go to step 25.
25. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
26. Disconnect the injector 2P connector from the problem cylinder.
27. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
28. Measure the voltage between injector 2P connector terminal No. 1 and body ground.
Is there battery voltage?
YES - Go to step 29.
NO - Repair open in the wire between the injector and PGM-FI main relay 1, then go to step 44.
29. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
30. 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 44.
NO - Go to step 31.
31. Check for continuity between appropriate injector 2P connector terminal No. 2 and the 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 32.
NO - Repair open in the wire between the PCM and the injector, then go to step 44.
32. 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 33.
NO - Replace the injector, Service and Repair then go to step 44.
33. 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.
34. Reconnect all connectors, and install the intake manifold. Intake Manifold Removal and Installation
35. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
36. Clear the DTCs with the HDS.
37. Start the engine, and let it idle without load (in P or N) for 2 minutes.
38. 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
39. 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 40.
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.
40. 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 44.
NO - Go to step 41.
41. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
42. Do an engine compression and a cylinder leak down test. Testing and Inspection
Did the engine pass both tests?
YES - Go to step 43.
NO - Repair the engine, then go to step 44.
43. Do the VTEC rocker arm test. VTEC Rocker Arm Test
Did the engine pass the test?
YES - Go to step 52.
NO - Repair the VTEC rocker arm, then go to step 44.
44. Reconnect all connectors.
45. Reset the PCM with the HDS.
46. Clear the CKP pattern with the HDS.
47. Do the PCM idle learn procedure. PCM Idle Learn Procedure
48. Do the CKP pattern learn procedure. Initial Inspection and Diagnostic Overview
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 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 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 screen 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 screen 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 screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 49.
52. Reconnect all connectors.
53. Update the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM. Initial Inspection and Diagnostic Overview
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)
- GEAR POSITION
- ECT SENSOR 1
55. 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, Initial Inspection and Diagnostic Overview then go to step 54. If the PCM was substituted, go to step 1.
NO - Go to step 56.
56. 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. PCM Replacement If any other Pending or Confirmed DTCs were indicated in step 55, go to the indicated DTC's troubleshooting.
NO - If the screen 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, Initial Inspection and Diagnostic Overview then go to step 54. 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 54.