- Start engine and listen for clicking sound at fuel injector in suspect cylinder. If injector clicks, go to next step. If injector does not click, check for open or short in harness between suspect fuel injector and PCM. See WIRING DIAGRAMS article. If wiring is okay, replace fuel injector, and recheck. If symptom or DTC is gone, replace original fuel injector. If DTC resets, substitute known-good PCM and recheck. If symptom or DTC is gone, replace original PCM.
- Check and record freeze frame data. Perform PCM reset procedure and clear DTC(s). See PCM RESET PROCEDURE/CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. Exchange spark plug from suspect cylinder with one from another cylinder. Connect scan tool. Test drive vehicle several times in freeze frame data range. If there is no freeze frame data of misfiring, test drive vehicle under various conditions and try to duplicate malfunction. If DTCs P0301, P0302, P0303, P0304, P0305, P0306 or temporary DTC P1399 are set, go to next step. If DTCs P0301, P0302, P0303, P0304, P0305, P0306 or temporary DTC P1399 are not set, problem is intermittent, possibly due to fouling spark plug. Misfire is not detected at this time. If misfire follows spark plug to different cylinder, replace spark plug. If misfire remains in same cylinder, go to next step.
- Remove ignition coil cover. Exchange ignition coil from suspect cylinder with one from another cylinder. Let engine idle for two minutes. Test drive vehicle several times in freeze frame data range. If DTCs P0301, P0302, P0303, P0304, P0305, P0306 or temporary DTC P1399 are set, go to next step. If DTCs P0301, P0302, P0303, P0304, P0305, P0306 or temporary DTC P1399 are not set, problem is intermittent, possibly due to ignition coil fouling. If misfire followed ignition coil that was exchanged, replace ignition coil. If misfire stayed in same cylinder, go to next step.
- Turn ignition off. Disconnect ignition coil 3-pin connector from suspect cylinder. See Fig 1. Turn ignition back on. Measure voltage in Black/Yellow wire between ground and ignition coil 3-pin harness connector terminal No. 3. If voltage is present go to next step. If voltage is not present, repair open or short in Black/Yellow wire between ignition coil 3-pin harness connector terminal No. 3 and fuse No. 11 (15-amp) in underdash fuse/relay box. See WIRING DIAGRAMS article. Repair as necessary.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
- Turn ignition off. Check for continuity between ground and ignition coil 3-pin harness connector terminal No. 2 (Black wire). See Fig 1. If continuity is present, go to next step. If continuity is not present, repair open in Black wire between ground and ignition coil 3-pin harness connector terminal No. 2.
- Disconnect PCM 31-pin connector. Check for continuity between ground and PCM 31-pin connector terminal(s). See DTC/PCM 31-PIN TERMINAL IDENTIFICATION table. If no continuity is present, go to next step. If continuity is present, repair short in wire between PCM 31-pin harness connector and ignition coil 3-pin harness connector.
DTC/PCM 31-PIN TERMINAL IDENTIFICATION
| Suspect Cylinder |
DTC |
PCM Terminal No. |
Wire Color |
| No. 1 (MDX) |
P0301 |
C4 |
Yellow/Light Green |
| No. 1 (3.2CL & 3.2TL) |
P0301 |
C4 |
Yellow/Green |
| No. 2 |
P0302 |
C14 |
Blue/Red |
| No. 3 |
P0303 |
C3 |
White/Blue |
| No. 4 |
P0304 |
C13 |
Brown |
| No. 5 |
P0305 |
C12 |
Black/Red |
| No. 6 |
P0306 |
C23 |
Brown/White |
- Reconnect PCM 31-pin harness connector. Connect fused jumper wire between ground and suspect ignition coil 3-pin harness connector terminal No. 1. See Fig 1. See DTC/IGNITION COIL TERMINAL IDENTIFICATION table. Check for continuity between ground and PCM 31-pin connector terminal(s). See DTC/PCM 31-PIN TERMINAL IDENTIFICATION table. If continuity is present, go to next step. If continuity is not present, repair open wire between PCM 31-pin harness connector and ignition coil 3-pin harness connector. See WIRING DIAGRAMS article. Repair as necessary.
DTC/IGNITION COIL TERMINAL IDENTIFICATION
| Suspect Cylinder |
DTC |
Wire Color |
| No. 1 (MDX) |
P0301 |
Yellow/Light Green |
| No. 1 (3.2CL & 3.2TL) |
P0301 |
Yellow/Green |
| No. 2 |
P0302 |
Blue/Red |
| No. 3 |
P0303 |
White/Blue |
| No. 4 |
P0304 |
Brown |
| No. 5 |
P0305 |
Black/Red |
| No. 6 |
P0306 |
Brown/White |
- Disconnect PCM 25-pin harness connector. Turn ignition on. Measure voltage between ground and PCM 25-pin connector terminal(s). See PCM 25-PIN TERMINAL IDENTIFICATION table. If battery voltage is present, go to next step. If battery voltage is not present, go to step 12.
DTC/PCM 25-PIN TERMINAL IDENTIFICATION
| Suspect Cylinder |
DTC |
PCM Terminal No. |
Wire Color |
| No. 1 |
P0301 |
B11 |
Brown |
| No. 2 |
P0302 |
B5 |
Red |
| No. 3 |
P0303 |
B15 |
Blue |
| No. 4 |
P0304 |
B4 |
Yellow |
| No. 5 |
P0305 |
B3 |
Black/Red |
| No. 6 |
P0306 |
B6 |
White/Blue |
- Disconnect fuel injector 2-pin connector on suspect cylinder. Measure resistance between fuel injector terminals No. 1 and No. 2. If resistance reading is 10-13 ohms, go to next step. If resistance reading is not 10-13 ohms, replace fuel injector.
- Exchange fuel injector from suspect cylinder with one from another cylinder. Let engine idle for 2 minutes. Test drive vehicle several times in freeze frame data range. If there is no freeze frame data of misfiring, test drive vehicle under various conditions and try to duplicate malfunction.
- If DTC P0301, P0302, P0303, P0304, P0305 or P0306 is not indicated, misfire condition is not detected at this time. Possible intermittent fuel injector poor connection. If misfire follows injector to another cylinder, replace faulty fuel injector. If misfire remains in same cylinder, check engine compression. Repair as necessary. If compression is okay, substitute known-good PCM, then recheck. If symptom or indication goes away, replace original PCM.
- Turn ignition off. Disconnect fuel injector 2-pin connector from suspect cylinder. Measure voltage between ground and fuel injector 2-pin connector terminal No. 1 (Yellow/Black wire). If battery voltage is present, go to next step. If battery voltage is not present, check for open in harness between PGM-FI main relay and fuel injector 2-pin harness connector. See WIRING DIAGRAMS article. Repair as necessary.
- Turn ignition off. Check continuity between ground and PCM 25-pin harness connector terminal(s). See DTC/PCM 25-PIN TERMINAL IDENTIFICATION table. If continuity is not present, go to next step. If continuity is present, repair short in wiring between PCM 25-pin harness connector and fuel injector 2-pin harness connector.
- Connect fused jumper wire between ground and fuel injector 2-pin harness connector terminal No. 2. See DTC/FUEL INJECTOR TERMINAL IDENTIFICATION table. Check for continuity between ground and PCM 25-pin harness connector(s). See DTC/PCM 25-PIN TERMINAL IDENTIFICATION table. If continuity is present, replace fuel injector. If continuity is not present, repair open wire between PCM 25-pin harness connector and fuel injector 2-pin harness connector terminal No. 2.
DTC/FUEL INJECTOR TERMINAL IDENTIFICATION
| Suspect Cylinder |
DTC |
Wire Color |
| No. 1 |
P0301 |
Brown |
| No. 2 |
P0302 |
Red |
| No. 3 |
P0303 |
Blue |
| No. 4 |
P0304 |
Yellow |
| No. 5 |
P0305 |
Black/Red |
| No. 6 |
P0306 |
White/Blue |