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
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.
- If the misfire is frequent enough to trigger detection of increased emissions during two consecutive driving cycles, the MIL comes on, and DTC P0300 (and some combination of P0301 through P0306) are stored.
- If the misfire is frequent enough to damage the catalyst, the MIL will blink whenever the misfire occurs, and DTC P0300 (and some combination of P0301 through P0306) are stored. When the misfire stops, the MIL stays on.
- Troubleshoot the following DTCs first, if any of them were stored along with the random misfire DTC(s) (Because parts can sometimes fail without setting DTCs, you should also do a physical inspection of the systems listed below):
P0101, P0102, P0103: MAF sensor
P0107, P0108, P1128, P1129: MAP sensor
P0171, P0172, P0174, P0175: Fuel system
P0335, P0339: CKP sensor
P0365, P0369: CMP sensor
P0400, P0401, P0404, P0406, P2413: EGR system
P0506, P0507: Idle control 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, 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, 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
- VSS
- REL TP SENSOR
- CLV (calculated load value)
- ECT SENSOR 1
- APP SENSOR
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, go to step 6 and recheck.
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.�
9. Turn the ignition switch to LOCK (0).
10. Check the fuel quality.
Is the fuel quality OK?
YES -
Go to step 11.
NO -
Drain the fuel tank, fill it with known-good fuel, then go to step 18.
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)
- ECT SENSOR 1
- APP SENSOR
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 -
Go to step 18.
14. Check the fuel pressure Testing and Inspection.
Is the fuel pressure OK?
YES -
Go to step 15.
NO -
- If the pressure is too high, replace the fuel pressure regulator Service and Repair, then go to step 18.
- If the pressure is too low, check for restrictions in the fuel pump, the fuel feed lines, and the fuel filter. If they are OK, replace the fuel pressure regulator Service and Repair, then go to step 18.
15. Start the engine. Hold the engine speed at 3,000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.
16. Check under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 176 °F (80 °C)
- Transmission in P or N
- All electrical loads off
17. Monitor the ENGINE SPEED in the DATA LIST with the HDS. Raise the engine speed, and hold it at 2,500±100 rpm. While holding the rpm steady, check the MAF SENSOR in the DATA LIST.
Is there about 10.3-12.5 gm/s?
YES -
Replace the injectors Service and Repair, then go to step 18.
NO -
Replace the MAF sensor/IAT sensor, then go to step 18.
18. Turn the ignition switch to ON (II).
19. Reset the PCM with the HDS.
20. Do the PCM idle learn procedure PCM Idle Learn Procedure.
21. Do the CKP pattern clear/CKP pattern learn procedure.
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)
- ECT SENSOR 1
- APP SENSOR
23. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0300 and any combination of 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 DTC P0301, P0302, P0303, P0304, P0305, or P0306 troubleshooting.
NO -
Go to step 24.
24. 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 23, go to the indicated DTC's troubleshooting.�
NO -
If the HDS indicates FAILED, check for poor connection or loose terminals at the ignitions 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, go to step 22.