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

Special Tools Required

Pressure Gauge Adapter 07NAJ-P07010A
A/T Low Pressure Gauge w/Panel 07406-0070301
AT 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 (see GENERAL TROUBLESHOOTING INFORMATION ).
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 P0306) 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 combination of P0301 through P0306) 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) (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

P0506, P0507: Idle control system

P0365, P0369: CMP sensor

P0401, P0404, P0406, P2413: EGR system

P2646, P2647, P2648, P2649: VTEC system

Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
Clear the DTC with the HDS.
Start the engine, and let it idle without load (A/T in P or N, M/Tin neutral).
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, then recheck.
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.
Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VEHICLE SPEED
- REL TP SENSOR
- CLV (calculated load value)
- ECT SENSOR 1
- APP SENSOR
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 and recheck.
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. ■
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
Check the fuel quality.
Is the quality good?

YES - Go to step 11.

NO - Drain the fuel tank, and fill it with known-good fuel, then go to step 23.
Inspect the spark plugs (see SPARK PLUG INSPECTION ). If the spark plugs are fouled or worn, replace them.
Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VEHICLE SPEED
- REL TP SENSOR
- CLV (calculated load value)
- ECT SENSOR 1
- APP SENSOR
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 23.
Check the fuel pressure (see FUEL PRESSURE TEST ).
Is the fuel pressure OK?

YES - Go to step 15.

NO -
- If the pressure is too high, replace the fuel pressure regulator; without SH-AWD (see FUEL PRESSURE REGULATOR REPLACEMENT ), with SH-AWD (see FUEL PRESSURE REGULATOR REPLACEMENT ), then go to step 23.
- If the pressure is too low, check the fuel pump, the fuel feed lines, and the fuel filter. If they are OK, replace the fuel pressure regulator; without SH-AWD (see FUEL PRESSURE REGULATOR REPLACEMENT ), with SH-AWD (see FUEL PRESSURE REGULATOR REPLACEMENT ), then go to step 23.
Start the engine. Hold the engine speed at 3, 000 RPM without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.
Check under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 176°F (80°C)
- A/T in N, M/T in neutral
- All electrical loads off
Monitor the ENGINE SPEED in the DATA LIST with the HDS, and hold the engine speed at 2, 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 2, 500 RPM?

YES - Repeat step 17.

NO - Go to step 18.
While holding the engine speed at 2, 500 RPM, check the MAF SENSOR in the DATA LIST with the HDS.
Is there about 11.0- 15.5 gm/s (J35Z6 engine) or 11.8- 16.6 gm/s (J37A4 engine)?

YES - Go to step 19.

NO - Replace the MAF sensor/IAT sensor , then go to step 23.
Remove the rocker arm oil pressure switch (A), and attach the special tools as shown in illustration below, then attach the rocker arm oil pressure switch to the pressure gauge adapter (B).

Fig 1: Rocker Arm Oil Pressure Switch And Pressure Gauge Adapter With Torque Specifications
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Reconnect the rocker arm oil pressure switch 2P connector.
Start the engine. Hold the engine speed at 3, 000 RPM without load (A/T in P or N, M/T in neutral) until the radiator fan comes on.
Check the oil pressure at engine speeds of 1, 000 and 2, 000 RPM. Keep the measuring time as short as possible (less than 1 minute) because the engine is running without load.
Is the oil pressure below 49 kPa (0.5 kgf/cm ² , 7 psi)?

YES - Remove the special tools, and reinstall the rocker arm oil pressure switch with a new O-ring, then go to step 23.

NO - Inspect the VTEC system, then go to step 23.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
Reset the ECM/PCM with the HDS.
Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
Do the CKP pattern clear/CKP pattern learn procedure (see CKP PATTERN CLEAR/CKP PATTERN LEARN ).
Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VEHICLE SPEED
- REL TP SENSOR
- CLV (calculated load value)
- ECT SENSOR 1
- APP SENSOR
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 ECM/PCM, then go to the DTC P0301, P0302, P0303, P0304, P0305, or P0306 troubleshooting (see DTC Troubleshooting ).

NO - Go to step 29.
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 28, go to the indicated DTC's troubleshooting. ■

NO - If the screen indicates FAILED, check for poor connection or loose terminals at the ignition coils, the injectors, and the ECM/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 27.