DTC Troubleshooting: 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.

DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P0641 Sensor Reference Voltage A Malfunction
      

1.
Problem verification:

Problem verification
?1.
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.
DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P0641 Sensor Reference Voltage A Malfunction
      

Is DTC P0641 indicated?

     
YES
     
     
     
The failure is duplicated. Go to step 2.
     
NO
     
     
     
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the PCM and these parts:?
APP sensor
MAP sensor
EGR valve
Output shaft (countershaft) speed sensor
A/C pressure sensor
FTP sensor
2.
Determine possible failure area (VCC lines, others):

Determine possible failure area (VCC lines, others):
?1.
Press the engine start/stop button to select the OFF mode.

?2.
Disconnect the connectors from these parts:

?3.
Press the engine start/stop button to select the ON mode.

?4.
Clear the DTC with the HDS.


?5.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P0641 Sensor Reference Voltage A Malfunction
      

Is DTC P0641 indicated?

     
YES
     
     
     
Go to step 4.
     
NO
     
     
     
Go to step 3.
3.
Shorted part check:

Shorted part check
?1.
Check for Pending or Confirmed DTCs with the HDS while reconnecting these parts, one at a time:
APP sensor
MAP sensor
EGR valve
Output shaft (countershaft) speed sensor
A/C pressure sensor
FTP sensor

DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P0641 Sensor Reference Voltage A Malfunction
      

Is DTC P0641 indicated?

     
YES
     
     
     
Replace the part that caused the DTC when it was reconnected, then do the repair verification.
     
NO
     
     
     
Check for poor connections or loose terminals at the PCM and the following parts, then go to step 1.
APP sensor
MAP sensor
EGR valve
Output shaft (countershaft) speed sensor
A/C pressure sensor
FTP sensor
4.
Shorted wire check (VCC lines):

Shorted wire check (VCC lines)
?1.
Press the engine start/stop button to select the OFF mode.

?2.
Jump the SCS line with the HDS.


?3.
Disconnect the following connectors.

?4.
Check for continuity between these test points and body ground individually.
Test condition
OFF mode
APP sensor 6P connector: disconnected
MAP sensor 3P connector: disconnected
EGR valve 5P connector: disconnected
Output shaft (countershaft) speed sensor 3P connector: disconnected
A/C pressure sensor 3P connector: disconnected
FTP sensor 3P connector: disconnected
PCM connector A (51P): disconnected
PCM connector C (51P): disconnected

Connector
Test circuit
Terminal
PCM connector C (51P)
VCC1
No. 32 (PNK)
PCM connector A (51P)
VCC3
No. 41 (BRN)
PCM connector A (51P)
VCC6
No. 19 (BRN)



Is there continuity?

     
YES
     
     
     
Repair a short in the VCC wire between the PCM (A19, A41, or C32) and each part that was disconnected in step 2, then do the repair verification.
     
NO
     
     
     
Update the PCM if it does not have the latest software, or substitute a known-good PCM, then do the repair verification.
Repair verification:

?1.
Press the engine start/stop button to select the OFF mode.

?2.
Reconnect all connectors.

?3.
Exit the SCS mode with the HDS.


?4.
Press the engine start/stop button to select the ON mode.

?5.
Reset the PCM with the HDS.


?6.
Do the PCM idle learn procedure.

?7.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P0641 Sensor Reference Voltage A Malfunction
      


Is DTC P0641 indicated?

     
YES
     
     
     
If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, check for poor connections or loose terminals at the PCM and the following parts, then go to step 1.
APP sensor
MAP sensor
EGR valve
Output shaft (countershaft) speed sensor
A/C pressure sensor
FTP sensor
     
NO
     
     
     
If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.?