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DTC P0641 Or DTC P0651

Code Definition

CAUTION: When substituting or replacement of PCM is recommended, see PCM REMOVAL & REPLACEMENT  for important precautions.
NOTE: This test covers both "A" and "B" sensor reference voltage circuit malfunctions. The information will be shown "A" first and "B" second. When discussion arises, "A" sensors and circuit terminals will precede "B" sensors and circuit terminals. Furthermore "B" sensors and circuit terminals information will be enclosed in parantheses ( ).
  1. Turn ignition on. Using Honda PGM Tester or the HDS, do the DTC CLEAR in the CLEAR menu.
  2. Check for Temporary DTCs or DTCs in the DTC menu. If DTC P0641 is set, go to step  3 . Or if DTC P0651 is set, go to step  12 . If DTCs P0641 and/or P0651 are not set, problem is intermittent, system is OK at this time. Check for poor connections or loose terminals at the following connectors:
    • MAP Sensor
    • APP sensor 1
    • Countershaft Speed Sensor
    • (Throttle Actuator Control Module)
    • (Mainshaft Speed Sensor)
    • (EGR Valve Position Sensor)
    • (APP Sensor 2)
    • (FTP Sensor)
  3. Turn ignition off. Disconnect MAP sensor 3-pin connector.
  4. Turn ignition on. Using Honda PGM Tester or the HDS, do the DTC CLEAR in the CLEAR menu.
  5. Check for Temporary DTCs or DTCs in the DTC menu. If DTC P0641 is set, go to step  6 . If DTC P0641 is not set, replace MAP sensor and go to step  35 .
  6. Turn ignition off. Disconnect APP sensor 1 6-pin connector.
  7. Turn ignition on. Using Honda PGM Tester or the HDS, do the DTC CLEAR in the CLEAR menu.
  8. Check for Temporary DTCs or DTCs in the DTC menu. If DTC P0641 is set, go to step  9 . If DTC P0641 is not set, replace APP sensor 1 and go to step  35 .
  9. Turn ignition off. Disconnect (countershaft speed sensor) 3-pin connector.
  10. Turn ignition on. Using Honda PGM Tester or the HDS, do the DTC CLEAR in the CLEAR menu.
  11. Check for Temporary DTCs or DTCs in the DTC menu. If DTC P0651 is set, go to step  32 . If DTC P0651 is not set, replace (countershaft speed sensor) and go to step  40 .
  12. Turn ignition off.
  13. Disconnect (throttle actuator control module) 16-pin connector.
  14. Turn ignition on. Using Honda PGM Tester or the HDS, do the DTC CLEAR in the CLEAR menu.
  15. Check for Temporary DTCs or DTCs in the DTC menu. If DTC P0651 is set, go to next step. If DTC P0651 is not set, replace (throttle actuator control module) and go to step  40 .
  16. Turn ignition off.
  17. Disconnect (mainshaft speed sensor) 3-pin connector.
  18. Turn ignition on. Using Honda PGM Tester or the HDS, do the DTC CLEAR in the CLEAR menu.
  19. Check for Temporary DTCs or DTCs in the DTC menu. If DTC P0651 is set, go to next step. If DTC P0651 is not set, replace (mainshaft speed sensor) and go to step  40 .
  20. Turn ignition off.
  21. Disconnect (EGR position sensor) 5-pin connector.
  22. Turn ignition on. Using Honda PGM Tester or the HDS, do the DTC CLEAR in the CLEAR menu.
  23. Check for Temporary DTCs or DTCs in the DTC menu. If DTC P0651 is set, go to next step. If DTC P0651 is not set, replace (EGR position sensor) and go to step  40 .
  24. Turn ignition off.
  25. Disconnect (APP sensor 2) 6-pin connector.
  26. Turn ignition on. Using Honda PGM Tester or the HDS, do the DTC CLEAR in the CLEAR menu.
  27. Check for Temporary DTCs or DTCs in the DTC menu. If DTC P0651 is set, go to next step. If DTC P0651 is not set, replace (APP sensor 2) and go to step  40 .
  28. Turn ignition off.
  29. Disconnect (FTP sensor) 3-pin connector.
  30. Turn ignition on. Using Honda PGM Tester or the HDS, do the DTC CLEAR in the CLEAR menu.
  31. Check for Temporary DTCs or DTCs in the DTC menu. If DTC P0651 is set go to next step. If DTC P0651 is not set, replace (FTP sensor) and go to step  40 .
  32. Turn ignition off. Disconnect PCM harness connector "A".
  33. Disconnect PCM harness connector "B".
  34. Check for continuity between ground and PCM harness connector terminals A7 (A27), B43 (B29) and B46. If there is continuity, repair short in wire between ground and PCM harness connector terminals A7 (A27), B43 (B29) and B46. If there is no continuity, go to step  40 .
  35. Turn ignition on.
  36. With the Honda PGM tester or the HDS, do PCM RESET in the CLEAR menu. Go to next step.
  37. Do the PCM idle learn procedure. See PCM IDLE LEARN PROCEDURE  .
  38. Check for Temporary DTCs or DTCs in the DTC menu. If DTCs P0641 or DTC P0651 are set, check for poor connections or loose terminals at the PCM and the following connectors:
    • MAP Sensor
    • APP Sensor 1
    • Countershaft Speed Sensor
    • (Throttle Actuator Control Module)
    • (Mainshaft Speed Sensor)
    • (EGR Valve Position Sensor)
    • (APP Sensor 2)
    • (FTP Sensor)
    After checking above list. Go to step  1 . If any other Temporary DTCs or DTCs are set, go to the indicated DTC and troubleshoot. If DTCs P0641 or DTC P0651 are not set, troubleshooting is done.
  39. Update the PCM if it does not have the latest software, or substitute a known-good PCM. Do the PCM idle learn procedure. See PCM IDLE LEARN PROCEDURE  .
  40. Check for Temporary DTCs or DTCs in the DTC menu. If DTCs P0641 or DTC P0651 are set, check for poor connections or loose terminals at the PCM and the following connectors:
    • MAP Sensor
    • APP Sensor 1
    • Countershaft Speed Sensor
    • (Throttle Actuator Control Module)
    • (Mainshaft Speed Sensor)
    • (EGR Valve Position Sensor)
    • (APP Sensor 2)
    • (FTP Sensor)
    After checking above list. Go to step  1 . If any other Temporary DTCs or DTCs are set, go to the indicated DTC and troubleshoot. If DTCs P0641 or DTC P0651 are not set and PCM was updated, troubleshooting is done. If PCM was substituted, replace original PCM.
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