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
- Turn the ignition switch to ON (II).
- 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, 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 idling until a result comes on. If the screen indicates OUT OF CONDITION, wait several minutes, and recheck.
- 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.
- Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- 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.
- 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, the system is OK at this time. Check for the fuel and ignition system circuit connectors for poor connections or loose terminals.
- Turn the ignition switch to LOCK (0).
- Remove the engine cover (see REMOVAL ).
- Start the engine, and listen for a clicking sound at the injector of the problem cylinder.
Does the injector click?
YES -Go to step 12.
NO -Go to step 43.
- Turn the ignition switch to LOCK (0).
- Exchange the ignition coil from the problem cylinder with one from another cylinder.
- Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- 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 16.
NO -Intermittent misfire due to poor contact at an ignition coil connector (no misfire at this time). Check for poor connections or loose terminals at the ignition coils.
- Determine which cylinder had the misfire.
Does the misfire occur in the cylinder where the ignition coil was exchanged?
YES -Replace the faulty ignition coil (see IGNITION COIL REMOVAL/INSTALLATION ), then go to step 63.
NO -Go to step 17.
- Turn the ignition switch to LOCK (0).
- Exchange the spark plug from the problem cylinder with one from another cylinder.
- Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- 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 21.
NO -Intermittent misfire due to spark plug fouling (no misfire at this time).
- Determine which cylinder had the misfire.
Does the misfire occur in the cylinder where the spark plug was exchanged?
YES -Replace the faulty spark plug, then go to step 62.
NO -Go to step 22.
- Turn the ignition switch to LOCK (0).
- Exchange the injector from the problem cylinder with one from another cylinder.
- Start the engine, and let it idle for 2 minutes.
- Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- 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 27.
NO -Intermittent misfire due to bad contact at an injector connector (no misfire at this time). Check for poor connections or loose terminals at the injectors.
- Determine which cylinder had the misfire.
Does the misfire occur in the cylinder where the injector was exchanged?
YES -Replace the faulty injector (see INJECTOR REPLACEMENT ), then go to step 63.
NO -Go to step 28.
- Turn the ignition switch to LOCK (0).
- Disconnect the ignition coil 3P connector from the problem cylinder.
- Turn the ignition switch to ON (II).
- Measure the voltage between ignition coil 3P connector terminal No. 3 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there battery voltage?
YES -Go to step 32.
NO -Repair open in the wire between the ignition coil and the No. 16 IGN RLY (15 A) fuse, then go to step 63.
- Turn the ignition switch to LOCK (0).
- Check for continuity between ignition coil 3P connector terminal No. 2 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Go to step 34.
NO -Repair open in the wire between the ignition coil and G102, then go to step 63.
- Turn the ignition switch to LOCK (0).
- Jump the SCS line with the HDS.
- Disconnect ECM/PCM connector A (31P).
- Check for continuity between body ground and the appropriate ECM/PCM connector terminal (see table).TERMINAL REFERENCE CHART
PROBLEM CYLINDER DTC ECM/PCM TERMINAL WIRE COLOR No. 1 P0301 A16 YEL/GRN No. 2 P0302 A15 BLU/RED No. 3 P0303 A14 WHT/BLU No. 4 P0304 A13 BRN Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Repair short in the wire between the ECM/PCM and the ignition coil, then go to step 63.
NO -Go to step 38.
- Connect appropriate ignition coil 3P connector terminal No. 1 to body ground with a jumper wire (see table).WIRE COLOR REFERENCE CHART
PROBLEM CYLINDER DTC WIRE COLOR No. 1 P0301 YEL/GRN No. 2 P0302 BLU/RED No. 3 P0303 WHT/BLU No. 4 P0304 BRN - Check for continuity between body ground and the appropriate ECM/PCM connector terminal (see table).TERMINAL REFERENCE CHART
PROBLEM CYLINDER DTC ECM/PCM TERMINAL WIRE COLOR No. 1 P0301 A16 YEL/GRN No. 2 P0302 A15 BLU/RED No. 3 P0303 A14 WHT/BLU No. 4 P0304 A13 BRN Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Go to step 40.
NO -Repair open in the wire between the ECM/PCM and the ignition coil, then go to step 63.
- Reconnect the ignition coil 3P connector and ECM/PCM connector A (31P).
- Do an engine compression and a cylinder leakdown test (see ENGINE COMPRESSION INSPECTION
).
Did the engine pass both tests?
YES -Go to step 42.
NO -Repair the engine, then go to step 63.
- Do the VTEC rocker arm test (see VTEC ROCKER ARM TEST
).
Did the engine pass the test?
YES -Go to step 72.
NO -Repair the VTEC rocker arm (see ROCKER ARM ASSEMBLY REMOVAL ), then go to step 63.
- Turn the ignition switch to LOCK (0).
- Jump the SCS line with the HDS.
- Disconnect ECM/PCM connector B (24P).
- Turn the ignition switch to ON (II).
- Measure the voltage between body ground and the appropriate ECM/PCM connector terminal (see table).TERMINAL REFERENCE CHART
PROBLEM CYLINDER DTC ECM/PCM TERMINAL WIRE COLOR No. 1 P0301 B5 BRN No. 2 P0302 B4 RED No. 3 P0303 B3 BLU No. 4 P0304 B2 YEL Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there battery voltage?
YES -Go to step 56.
NO -Go to step 48.
- Turn the ignition switch to LOCK (0).
- Disconnect the injector 2P connector from the problem cylinder.
- Turn the ignition switch to ON (II).
- Measure the voltage between injector 2P connector terminal No. 1 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there battery voltage?
YES -Go to step 52.
NO -Repair open in the wire between the injector and PGM-FI main relay 1 (Fl MAIN), then go to step 63.
- Turn the ignition switch to LOCK (0).
- Check for continuity between body ground and the appropriate ECM/PCM connector terminal (see table).TERMINAL REFERENCE CHART
PROBLEM CYLINDER DTC ECM/PCM TERMINAL WIRE COLOR No. 1 P0301 B5 BRN No. 2 P0302 B4 RED No. 3 P0303 B3 BLU No. 4 P0304 B2 YEL Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Repair short in the wire between the ECM/PCM and the injector, then go to step 63.
NO -Go to step 54.
- Connect appropriate injector 2P connector terminal No. 2 to body ground with a jumper wire (see table).WIRE COLOR REFERENCE CHART
PROBLEM CYLINDER DTC WIRE COLOR No. 1 P0301 BRN No. 2 P0302 RED No. 3 P0303 BLU No. 4 P0304 YEL - Check for continuity between body ground and the appropriate ECM/PCM connector terminal (see table).TERMINAL REFERENCE CHART
PROBLEM CYLINDER DTC ECM/PCM TERMINAL WIRE COLOR No. 1 P0301 B5 BRN No. 2 P0302 B4 RED No. 3 P0303 B3 BLU No. 4 P0304 B2 YEL Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Go to step 56.
NO -Repair open in the wire between the ECM/PCM and the injector, then go to step 63.
- At the injector side, measure the resistance between injector 2P connector terminals No. 1 and No. 2.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there 10- 13 Ω?
YES -Go to step 57.
NO -Replace the injector (see INJECTOR REPLACEMENT ), then go to step 63.
- Install a known-good injector into the problem cylinder.
- Reconnect all connectors.
- Start the engine, and let it idle for 2 minutes.
- Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- 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 72.
NO -Replace the original injector (see INJECTOR REPLACEMENT ), then go to step 63.
- Turn the ignition switch to LOCK (0).
- Reconnect all connectors.
- Turn the ignition switch to ON (II).
- Reset the ECM/PCM with the HDS.
- Clear the CKP pattern with the HDS.
- Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
- Do the CKP pattern learn procedure (see CRANK (CKP) PATTERN CLEAR/CRANK (CKP) PATTERN LEARN ).
- Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0301, P0302, P0303, or P0304 indicated?
YES -Check for poor connections or loose terminals at the ignition coil(s), the injector(s), and the ECM/PCM, then go to the troubleshooting DTC P0300, P0301, P0302, P0303, or P0304 (see 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 ).
NO -Go to step 71.
- 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. If any other Temporary DTCs or DTCs were indicated in step 70, go to the indicated DTCs troubleshooting.
NO -If the screen indicates FAILED, check for poor connections or loose terminals at the ignition coil, the injector, 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 69.
- Update the ECM/PCM if it does not have the latest software (see ECM/PCM UPDATE ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ).
- Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0301, P0302, P0303, or P0304 indicated?
YES -Check for poor connections or loose terminals at the ignition coil(s), the injector(s), and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step 73. If the ECM/PCM was substituted, go to step 1.
NO -Go to step 75.
- Monitor the OBD STATUS for DTC P0301, P0302, P0303, or P0304 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ). If any other Temporary DTCs or DTCs were indicated in step 74, go to the indicated DTCs troubleshooting.
NO -If the screen indicates FAILED, check for poor connections or loose terminals at the ignition coil(s), the injector(s), and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step 73. If the ECM/PCM was substituted, 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 73.