DTC Troubleshooting
DTC P0641: Sensor Reference Voltage A MalfunctionNOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.
1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Go to step 4.
NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the PCM and these connectors:
- MAP sensor
- APP sensor
- Front/rear A/F sensor (Sensor 1)
- IMT actuator
- EGR valve
- FTP sensor
- Input shaft (mainshaft) speed sensor
- Output shaft (countershaft) speed sensor
4. Turn the ignition switch OFF.
5. Disconnect the MAP sensor 3P connector.
6. Turn the ignition switch ON (II).
7. Clear the DTC with the HDS.
8. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Go to step 9.
NO - Replace the MAP sensor, then go to step 53.
9. Turn the ignition switch OFF.
10. Disconnect the APP sensor 6P connector.
11. Turn the ignition switch ON (II).
12. Clear the DTC with the HDS.
13. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Go to step 14.
NO - Replace the APP sensor, then go to step 53.
14. Turn the ignition switch OFF.
15. Disconnect the front A/F sensor (Bank 2, Sensor 1) 8P connector.
16. Turn the ignition switch ON (II).
17. Clear the DTC with the HDS.
18. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Go to step 19.
NO - Replace the front A/F sensor (Bank 2, Sensor 1), then go to step 53.
19. Turn the ignition switch OFF.
20. Disconnect the rear A/F sensor (Bank 1, Sensor 1) 8P connector.
21. Turn the ignition switch ON (II).
22. Clear the DTC with the HDS.
23. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Go to step 24.
NO - Replace the rear A/F sensor (Bank 1, Sensor 1), then go to step 53.
24. Turn the ignition switch OFF.
25. Disconnect the IMT actuator 5P connector.
26. Turn the ignition switch ON (II).
27. Clear the DTC with the HDS.
28. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Go to step 29.
NO - Replace the IMT actuator, then go to step 53.
29. Turn the ignition switch OFF.
30. Disconnect the EGR valve 6P connector.
31. Turn the ignition switch ON (II).
32. Clear the DTC with the HDS.
33. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Go to step 34.
NO - Replace the EGR valve, then go to step 53.
34. Turn the ignition switch OFF.
35. Disconnect the FTP sensor 3P connector.
36. Turn the ignition switch ON (II).
37. Clear the DTC with the HDS.
38. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Go to step 39.
NO - Replace the FTP sensor, then go to step 53.
39. Turn the ignition switch OFF.
40. Disconnect the input shaft (mainshaft) speed sensor 3P connector.
41. Turn the ignition switch ON (II).
42. Clear the DTC with the HDS.
43. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Go to step 44.
NO - Replace the input shaft (mainshaft) speed sensor, then go to step 53.
44. Turn the ignition switch OFF.
45. Disconnect the output shaft (countershaft) speed sensor 3P connector.
46. Turn the ignition switch ON (II).
47. Clear the DTC with the HDS.
48. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Go to step 49.
NO - Replace the output shaft (countershaft) speed sensor, then go to step 53.
49. Turn the ignition switch OFF.
50. Jump the SCS line with the HDS.
51. Disconnect PCM connectors A (44P), B (44P), and C (44P).
52. Check for continuity between body ground and PCM connector terminals A19, A25, B18, B19, C12, and C13 individually.
Is there continuity?
YES - Repair short in the wire between the PCM (A19, A25, B18, B19, C12, or C13) and each sensor, then go to step 53.
NO - Go to step 59.
53. Turn the ignition switch OFF.
54. Reconnect all connectors.
55. Turn the ignition switch ON (II).
56. Reset the PCM with the HDS.
57. Do the PCM idle learn procedure.
58. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Check for poor connections or loose terminals at the PCM and these connectors:
- MAP sensor
- APP sensor
- Front/rear A/F sensor (Sensor 1)
- IMT actuator
- EGR valve
- FTP sensor
- Input shaft (mainshaft) speed sensor
- Output shaft (countershaft) speed sensor
After checking the above, go to step 1.
NO - Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTCs troubleshooting.
59. Reconnect all connectors.
60. Update the PCM if it does not have the latest software, or substitute a known-good PCM.
61. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0641 indicated?
YES - Check for poor connections or loose terminals at the PCM and these connectors:
- MAP sensor
- APP sensor
- Front/rear A/F sensor (Sensor 1)
- IMT actuator
- EGR valve
- FTP sensor
- Input shaft (mainshaft) speed sensor
- Output shaft (countershaft) speed sensor
If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, go to step 1.
NO - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTCs troubleshooting.