DTC Troubleshooting
DTC Troubleshooting: P0300
DTC P0300:
Random Misfire and Any Combination of the Following:
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
NOTE:
- Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information Initial Inspection and Diagnostic Overview.
- If the misfire is frequent enough to trigger detection of increased emissions during two consecutive driving cycles, the MIL will come on, and DTC P0300 (and some of the combination of P0301 through P0304) will be stored.
- If the misfire is frequent enough to damage the catalyst, the MIL will blink whenever the misfire occurs, and DTC P0300 (and some of the combination of P0301 through P0304) will be stored. When the misfire stops, the MIL will remain on.
- If any of the DTCs listed below are indicated at the same time as the random misfire DTCs, troubleshoot those DTCs first, then recheck for random misfire DTCs:
P0101, P0102, P0103: MAF sensor
P0106, P0107, P0108: MAP sensor
P0171, P0172: Fuel system
P0335, P0339: CKP sensor
P0351, P0352: Ignition coil
P0365, P0369: CMP sensor
P0401, P0404, P0416, P2413: EGR system
P0506, P0507: Idle control system
P1024, P1286, P1287, P1288, P1289, P128A, P128B, P2647, P2648, P2649, P2651, P2652, P2653, P2654, P3400: VTEC system
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).
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 driving until a result comes on. If the screen indicates OUT OF CONDITION, wait for several minutes, then 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
- ECT SENSOR 1
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.�
9. Turn the ignition switch to LOCK (0).
10. Check the fuel quality.
Is the quality good?
YES -
Go to step 11.
NO -
Drain the tank and fill with a known-good fuel, then go to step 15.
11. Inspect the spark plugs Testing and Inspection. If the spark plugs are fouled or worn, replace them.
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)
- APP SENSOR
- ECT SENSOR 1
13. 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 14.
NO -
Go to step 15.
14. Check the fuel pressure; '07-11 models Testing and Inspection.
Is the fuel pressure OK?
YES -
Check the fuel system lines and hoses for damage, leaks, and deterioration. Replace any damaged parts, then go to step 15.
NO -
- If the fuel pressure is too high, replace the fuel pressure regulator Service and Repair, then go to step 15.
- If the fuel pressure is too low, check the fuel pump, the fuel feed line, and the fuel filter. If they are OK, replace the fuel pressure regulator Service and Repair, then go to step 15.
15. Turn the ignition switch to ON (II).
16. Reset the PCM with the HDS.
17. Do the PCM idle learn procedure PCM Idle Learn Procedure.
18. Do the CKP pattern clear/CKP pattern learn procedure Initial Inspection and Diagnostic Overview.
19. 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
- ECT SENSOR 1
20. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0300, P0301, P0302, P0303, or P0304 indicated?
YES -
Check for a poor connection or loose terminals at the ignition coils, the injectors, and the PCM, then go to troubleshooting DTC P0301, P0302, P0303, or P0304 P0301.
NO -
Go to step 21.
21. 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 Pending or Confirmed DTCs were indicated in step 20, go to the indicated DTC's troubleshooting.�
NO -
If the screen indicates FAILED, go to step 1 and recheck. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 19.