DTC Troubleshooting: P0641 (K20C2 (CVT)) - Honda Civic FC/FK 2016-2021

DTC Troubleshooting: P0641

DTC P0641: Sensor Reference Voltage 1 Circuit Malfunction

NOTE:

	Before you troubleshoot, review the General Troubleshooting Information.
	This code is caused by an electrical circuit problem and cannot be caused by a mechanical problem in the transmission.

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
P0641 Sensor Reference Voltage 1 Circuit Malfunction

Problem verification:

Problem verification

?1.	Turn the vehicle to the ON mode.

?2.	Clear the DTC with the HDS.

?3.	Turn the vehicle to the OFF (LOCK) mode.

?4.	Turn the vehicle to the ON mode.

?5.

Check for Pending or Confirmed DTCs with the HDS.

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
P0641 Sensor Reference Voltage 1 Circuit 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 and loose terminals between the TCM and the following parts. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot.?

	CVT drive pulley speed sensor
	CVT driven pulley pressure sensor

Determine possible failure area (VCC lines, others):

Determine possible failure area (VCC lines, others)

?1.	Clear the DTC with the HDS.

?2.	Turn the vehicle to the OFF (LOCK) mode.

?3.

Disconnect the following connector.

CVT drive pulley speed sensor 3P connector

CVT driven pulley pressure sensor 3P connector

?4.	Turn the vehicle to the ON mode.

?5.

Check for Pending or Confirmed DTCs with the HDS.

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
P0641 Sensor Reference Voltage 1 Circuit Malfunction

Is DTC P0641 indicated?


	YES

Go to step 4.


	NO

Go to step 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:

	CVT drive pulley speed sensor
	CVT driven pulley pressure sensor

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
P0641 Sensor Reference Voltage 1 Circuit Malfunction

Is DTC P0641 indicated?


	YES

Replace the part that caused the DTC when it was reconnected.?


	NO

Check for poor connections and loose terminals at the TCM and the following parts, then go to step 1.

	CVT drive pulley speed sensor
	CVT driven pulley pressure sensor

Shorted wire check (VCC lines to ground):

Shorted wire check (VCC lines to ground)

?1.	Turn the vehicle to the OFF (LOCK) mode.

?2.

Disconnect the following connector.

TCM 50P connector

?3.

Check for continuity between these test points and body ground individually.

Test condition	Vehicle OFF (LOCK) mode
	CVT drive pulley speed sensor 3P connector: disconnected
	CVT driven pulley pressure sensor 3P connector: disconnected
	TCM 50P connector: disconnected

Connector	Terminal
TCM 50P connector	No. 17
TCM 50P connector	No. 18

Is there continuity?


	YES

Repair a short to ground in the VCC wire between the TCM and each part that was disconnected in step 2.?


	NO

Go to step 5.

Shorted wire check (VCC lines to power):

Shorted wire check (VCC lines to power)

?1.	Turn the vehicle to the ON mode.

?2.

Measure the voltage between these test points and body ground individually.

Test condition	Vehicle ON mode
	CVT drive pulley speed sensor 3P connector: disconnected
	CVT driven pulley pressure sensor 3P connector: disconnected
	TCM 50P connector: disconnected

Connector	Terminal
TCM 50P connector	No. 17
TCM 50P connector	No. 18

Is there battery voltage?


	YES

Repair a short to power in the VCC wire between the TCM and each part that was disconnected in step 2.?


	NO

The VCC wires are OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good TCM, then recheck. If this DTC goes away and the TCM was substituted, replace the original TCM.?