DTC Troubleshooting: P0300 (75) and P0301 (71), P0302 (72), P0303 (73), P0304 (74)

DTC P0300:  Random Misfire and Any Combination of the Following:
  
  
DTC P0302:  No. 2 Cylinder Misfire Detected
  
  
DTC P0304:  No. 4 Cylinder Misfire Detected

Special Tools Required
Oil pressure gauge attachment (  07NAJ-P070100)
 

Low pressure gauge (  07406-0070002)
 
Hose, oil pressure (  07ZAJ-S5A0200)
 


NOTE:
P0107, P0108: Manifold absolute pressure (MAP) sensor
P0171, P0172: Fuel system
P0335, P0339: Crankshaft position (CKP) sensor
P0365, P0369: Camshaft position (CMP) sensor

1.Note the this freeze data.
  • Engine speed
  • Vehicle speed
  • Throttle position
  • CLV
  • Gear position

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 9.


NO - If the screen indicates PASSED, go to 5. If the screen indicated EXECUTING, keep idling untill a result comes on. If the screen indicates OUT OF CONDITION, wait for several minutes, and 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 9.


NO - Go to 6.


6.Test-drive the vehicle for several minutes in the range of the recorded freeze data.

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 9.


NO - If the screen indicates PASSED, go to 8. If the screen indicated EXECUTING, keep driving untill a result comes on. If the screen indicates OUT OF CONDITION, go to 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 9.


NO - Intermittent failure, system is OK at this time.n


9.Turn the ignition switch OFF.

10.Check the fuel quality.

Is the quality good?


YES - Go to 11.


NO - Drain the tank, and fill with known-good fuel, then go to 20.


11.Inspect the spark plug. If the spark plugs are fouled or wom, replace them.

12.Test-drive the vehicle for several minutes in the range of the recorded freeze data.

13.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 14.


NO - Go to 20.

14.Check the fuel pressure.

Is the fuel pressure OK?


YES - Go to 15.


NO -


15.Turn the ignition switch OFF.

16.Remove the VTEC oil pressure switch (A) or the belt and install the special tools as shown, then install the VTEC oil pressure switch (A) or the belt in the pressure gauge adapter (B).

NOTE: Install the part in the reverse order of removal with a new O-ring.

 

17.Reconnect the VTEC oil pressure switch 2P connector.

18.Start the engine. Hold the engine at 3,000 rpm (min-1) without load (in Park or neutral) until the radiator fan comes on.

19.Check the oil pressure at engine speeds of 1,000 and 2,000 rpm (min-1). Keep the test time as short as possible (less than 1 minute) because the engine is running with no load.

Is the oil pressure below 49 kPa (0.5 kgf/cm2, 7 psi)?


YES - Check for air in the fuel line, then go to 20.


NO - Inspect the VTEC system oil line, then go to 20.


20.Turn the ignition switch ON (II).

21.Reset the ECM/PCM with the HDS.

22.Clear the CKP pattern with the HDS.

23.Do the ECM/PCM idle learn procedure.

24.Do the CKP pattern learn procedure.

25.Test-drive the vehicle for several minutes in the range of the recorded freeze data.

26.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 for poor connections 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 27.


27.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.n


NO - If the screen indicates PASSED, go to 1. If the screen indicated EXECUTING, keep driving untill a result comes on. If the screen indicates OUT OF CONDITION, go to 25 and recheck.