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 07406-0070300
- A/T pressure hose 07406-0020201
- A/T pressure hose, 2,210 mm 07MAJ-PY4011A
- A/T pressure adapter 07MAJ-PY40120
- Oil pressure hose 07ZAJ-S5A0200
NOTE:
- 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 flash 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.
- Troubleshoot the following DTCs first, if any of them were stored along with the random misfire DTC(s):
P0101, P0102, P0103: Mass air flow (MAF) sensor (2003-2004 SULEV, LX-P models and 2005-2006 models)
P0107, P0108, P1128, P1129: Manifold absolute pressure (MAP) sensor
P0171.P0172: Fuel system
P0335, P0339: Crankshaft position (CKP) sensor
P0365, P0369: Camshaft position (CMP) sensor B
P2646, P2647, P2648, P2649: VTEC system
P0506, P507: Idle control system
P0511: Idle air control (IAC) valve (2003-2005 models)
P0401, P0404, P0416, P2413: Exhaust gas recirculation (EGR) system
1. Record all freeze data and any on-board snapshot with the HDS.
2. Clear the DTC with the HDS.
3. Start the engine without load (in Park or neutral), then let it idle.
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 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
- Vehicle speed
- Throttle position
- CLV (calculated load value)
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 CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE show misfire counts?
YES - Go to step 9.
NO - Intermittent failure, system is OK at this time.
9. Turn the ignition switch OFF.
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. 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
- Vehicle speed
- Throttle position
- CLV (calculated load value)
13. Check the CYL.1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does 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.
Is the fuel pressure OK?
YES -
- 2003-2004 SULEV, LX-P models and 2005-2006 models: Go to step 15.
- 2003-2004 except SULEV, LX-P models: Go to step 19.
NO -
- If the fuel pressure is too high, replace the fuel pressure regulator; SULEV model, Non-SULEV model, 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; SULEV model, Non-SULEV model, then go to step 24.
15. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
16. Check for these conditions:
- Engine coolant temperature above 176 degree F (80 degree C)
- M/T in neutral (A/T in Park or neutral)
- All electric load off
17. Monitor the ENG SPD in the DATA LIST with the HDS, and hold the engine speed at 4,500 rpm. Once the engine speed is met, hold the accelerator pedal steady for more than 10 seconds.
Did the engine speed vary more than 100 rpm from 4,500 rpm?
YES - Repeat step 17.
NO - Go to step 18.
18. While holding the engine speed at 4,500 rpm, check the MAF SENSOR in the DATA LIST with the HDS.
Is there about 14 - 20 gm/s?
YES - Go to step 19.
NO - Replace the MAF sensor/IAT sensor, then go to step 24.
19. Turn the ignition switch OFF.
20. Remove the rocker arm oil pressure switch (VTEC oil pressure switch) (A), and install the special tools as shown, then install the rocker arm oil pressure switch (VTEC oil pressure switch) in the pressure gauge adapter (B).
NOTE: Install the switch in the reverse order of removal with a new O-ring.
21. Reconnect the rocker arm oil pressure switch (VTEC oil pressure switch) 2P connector.
22. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) 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. Keep the test time as short as possible (less than 1 minute) because the engine is running without load.
Is the oil pressure below 49 kPa (7 psi, 0.5 kgf/sq.cm)?
YES - Check for air in the fuel line, then go to step 24.
NO - Inspect the VTEC system, then go to step 24.
24. Turn the ignition switch ON (II).
25. Reset the ECM/PCM with the HDS.
26. Clear the CKP pattern with the HDS.Programming and Relearning
27. Do the ECM/PCM idle learn procedure.Programming and Relearning
28. Do the CKP pattern learn procedure.Programming and Relearning
29. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- Engine speed
- Vehicle speed
- Throttle position
- CLV (calculated load value)
30. Check for Temporary DTCs or DTCs with the HDS.
Are any Temporary DTCs or DTCs indicated?
YES - If DTC P0300, P0301, P0302, P0303, or P0304 are indicated, check fora poor connection or loose terminals at the ignition coil, the injector; and the ECM/PCM, then go to troubleshooting DTC P0301, P0302, P0303, or P0304. If any other Temporary DTCs or DTCs are indicated; go to the indicated DTC's troubleshooting.
NO - Go to step 31.
31. Monitor the OBD STATUS for DTC P8301, P0302, P0303, or P0304 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES - Troubleshooting is complete.
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 29 and recheck.