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
Special Tools Required
- Pressure Gauge Adapter 07NAJ-P07010A
- A/T Low Pressure Gauge w/Panel 07406-0070301
- A/T Pressure Test Hose 07AAJ-PY4A100
- A/T Pressure Adapter 07MAJ-PY40120
- Oil Pressure Hose 07ZAJ-S5AA200
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 combination of P0301 through P0304) are stored.
- If the misfire is frequent enough to damage the catalyst, the MIL will flash whenever the misfire occurs, and DTC P0300 (and some combination of P0301 through P0304) will be stored. When the misfire stops, the MIL stays 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
P0107, P0108: MAP sensor
P0171, P0172: Fuel system
P0335, P0339: CKP sensor
P0365, P0369: CMP sensor B
P0506, P0507: Idle control system
P2646, P2647, P2648, P2649: 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 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 or NOT COMPLETED, 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
7. Monitor the OBD STATUS for DTC P0301, P0302, P0303, or P0304 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 or NOT COMPLETED, go to step 6 P0300 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 24.
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
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 24.
14. Check the fuel pressure Testing and Inspection.
Is the fuel pressure OK?
YES -
Go to step 15.
NO -
- If the fuel pressure is too high, replace the fuel pressure regulator Service and Repair, then go to step 24.
- If the fuel pressure is too low, check the fuel pump, the fuel feed pipe, and the fuel filter. If they are OK, replace the fuel pressure regulator Service and Repair, then go to step 24.
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 for 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 and hold the engine speed steady at 2,500±100 rpm. While holding the engine speed steady, check the MAF sensor in the DATA LIST with the HDS.
Is there about 7.0-8.6 gm/s?
YES -
Go to step 18.
NO -
Replace the MAF sensor/IAT sensor Service and Repair, then go to step 24.
18. Turn the ignition switch to LOCK (0).
19. Remove the rocker arm oil pressure switch Service and Repair
20. Attach the special tools to the rocker arm oil control valve as shown, then attach the rocker arm oil pressure switch (A) to the pressure gauge adapter (B).
21. Reconnect the rocker arm oil pressure switch 2P connector.
22. 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.
23. Check the oil pressure at engine speeds of 1,000 rpm and 2,000 rpm.
Is the oil pressure below 49 kPa (0.5 kgf/cm2, 7 psi)?
YES -
Go to step 24.
NO -
Inspect the VTEC system, then go to step 24.
24. Turn the ignition switch to ON (II).
25. Reset the PCM with the HDS.
26. Do the CKP pattern clear procedure. Initial Inspection and Diagnostic Overview
27. Do the PCM idle learn procedure. PCM Idle Learn Procedure
28. Do the CKP pattern learn procedure. Initial Inspection and Diagnostic Overview
29. 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
30. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0300, P0301, P0302, P0303, or P0304 indicated?
YES -
Check for poor connections or loose terminals at the ignition coils, the injectors, and the PCM, then go to the troubleshooting for DTC P0301,P0302, P0303, or P0304 P0301.
NO -
Go to step 31.
31. Monitor the OBD STATUS for DTC P0301, P0302, P0303, or P0304 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 30 P0300, go to the indicated DTC's troubleshooting.�
NO -
If the HDS indicates FAILED, go to step 1 P0300 and recheck. If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION or NOT COMPLETED, go to step 29.