DTC Troubleshooting

DTC Troubleshooting: P0641, P0641

DTC P0641:

Sensor Reference Voltage A Malfunction

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information Initial Inspection and Diagnostic Overview.

1. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

2. Clear the DTC with the HDS.

3. Check for Pending or Confirmed 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 ECM/PCM and these parts:

- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor

4. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

5. Disconnect the connectors of these parts:

- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor

6. Turn the ignition switch ON (II), or press the engine start/stop button to select the ON mode.

7. Clear the DTC with the HDS.

8. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0641 indicated?

YES -

Go to step 10.

NO -

Go to step 9.

9. Check for Pending or Confirmed DTCs with the HDS while reconnecting these parts, one at a time:

- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor

Is DTC P0641 indicated?

YES -

Replace the part that caused the DTC when it was reconnected, then go to step 14.

NO -

Check for poor connections or loose terminals at the ECM/PCM and the following parts, then go to step 1.

- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor

10. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

11. Jump the SCS line with the HDS.

12. Disconnect ECM/PCM connectors A (49P), B (49P), and C (49P).

13. Check for continuity between body ground and ECM/PCM connector terminals A24, B18, and C12 individually.













Is there continuity?

YES -

Repair short in the wire between the ECM/PCM(A24, B18, or C12) and each part that was disconnected in step 5, then go to step 14.

NO -

Go to step 20.

14. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

15. Reconnect all connectors.

16. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

17. Reset the ECM/PCM with the HDS.

18. Do the ECM/PCM idle learn procedure ECM/PCM Idle Learn Procedure.

19. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0641 indicated?

YES -

Check for poor connections or loose terminals at the ECM/PCM and the following parts, then go to step 1.

- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor

NO -

Troubleshooting is complete. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.

20. Reconnect all connectors.

21. Update the ECM/PCM if it does not have the latest software ECM/PCM Update, or substitute a known-good ECM/PCM.

22. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0641 indicated?

YES -

If the ECM/PCM was updated, substitute a known-good ECM/PCM, then recheck. If the ECM/PCM was substituted, check for poor connections or loose terminals at the ECM/PCM and the following parts, then go to step 1.

- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor

NO -

If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM Service and Repair. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.