DTC Troubleshooting: P0641 (K20C1) - Honda Civic FC/FK 2016-2021

1.

Problem verification:

Problem verification

?1.	Turn the vehicle to 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
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. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot.?

	CKP sensor
	CMP sensor A
	CMP sensor B
	Output shaft (countershaft) speed sensor
	Fuel rail pressure sensor
	MAF sensor/IAT sensor 1
	MAP sensor/IAT sensor 2
	Rocker arm oil pressure sensor
	Turbocharger boost sensor
	Turbocharger
	Throttle body
	APP sensor
	Input shaft (mainshaft) speed sensor
	Neutral position sensor
	A/C pressure sensor
	FTP sensor (KA/KC)

2.

Determine possible failure area (VCC lines, others):

Determine possible failure area (VCC lines, others)

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

?2.

Disconnect the following connectors.

CKP sensor 3P connector

CMP sensor A 3P connector

CMP sensor B 3P connector

Output shaft (countershaft) speed sensor 3P connector

Fuel rail pressure sensor 5P connector

MAF sensor/IAT sensor 1 5P connector

MAP sensor/IAT sensor 2 4P connector

Rocker arm oil pressure sensor 3P connector

Turbocharger boost sensor 3P connector

Turbocharger 5P connector

Throttle body 6P connector

APP sensor 6P connector

Input shaft (mainshaft) speed sensor 3P connector

Neutral position sensor 4P connector

A/C pressure sensor 3P connector

FTP sensor 3P connector (KA/KC)

?3.	Turn the vehicle to 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
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:

	CKP sensor
	CMP sensor A
	CMP sensor B
	Output shaft (countershaft) speed sensor
	Fuel rail pressure sensor
	MAF sensor/IAT sensor 1
	MAP sensor/IAT sensor 2
	Rocker arm oil pressure sensor
	Turbocharger boost sensor
	Turbocharger
	Throttle body
	APP sensor
	Input shaft (mainshaft) speed sensor
	Neutral position sensor
	A/C pressure sensor
	FTP sensor (KA/KC)

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

Is DTC P0641 indicated?


	YES

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


	NO

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

	CKP sensor
	CMP sensor A
	CMP sensor B
	Output shaft (countershaft) speed sensor
	Fuel rail pressure sensor
	MAF sensor/IAT sensor 1
	MAP sensor/IAT sensor 2
	Rocker arm oil pressure sensor
	Turbocharger boost sensor
	Turbocharger
	Throttle body
	APP sensor
	Input shaft (mainshaft) speed sensor
	Neutral position sensor
	A/C pressure sensor
	FTP sensor (KA/KC)

4.

Shorted wire check (VCC lines):

Shorted wire check (VCC lines)

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

?2.	Jump the SCS line with the HDS, and wait more than 1 minute.

?3.

Disconnect the following connectors.

PCM connector No. 1 (96P)

PCM connector No. 2 (58P)

?4.

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

Test condition	Vehicle OFF (LOCK) mode
	CKP sensor 3P connector: disconnected
	CMP sensor A 3P connector: disconnected
	CMP sensor B 3P connector: disconnected
	Output shaft (countershaft) speed sensor 3P connector: disconnected
	Fuel rail pressure sensor 5P connector: disconnected
	MAF sensor/IAT sensor 1 5P connector: disconnected
	MAP sensor/IAT sensor 2 4P connector: disconnected
	Rocker arm oil pressure sensor 3P connector: disconnected
	Turbocharger boost sensor 3P connector: disconnected
	Turbocharger 5P connector: disconnected
	Throttle body 6P connector: disconnected
	APP sensor 6P connector: disconnected
	Input shaft (mainshaft) speed sensor 3P connector: disconnected
	Neutral position sensor 4P connector: disconnected
	A/C pressure sensor 3P connector: disconnected
	FTP sensor 3P connector (KA/KC): disconnected
	PCM connector No. 1 (96P): disconnected
	PCM connector No. 2 (58P): disconnected

Connector	Terminal
PCM connector No. 1 (96P)	No. 61, No. 62, No. 63, No. 64, No. 65, No. 66, No. 67, No. 80, No. 81, No. 82, and No. 83
PCM connector No. 2 (58P)	No. 41, No. 46, No. 55, and No. 58

Is there continuity?


	YES

Repair a short in the VCC wire(s) between PCM connector No. 1 terminal(s) (No. 61, No. 62, No. 63, No. 64, No. 65, No. 66, No. 67, No. 80, No. 81, No. 82, and/or No. 83), PCM connector No. 2 terminal(s) (No. 41, No. 46, No. 55, and/or No. 58) and each part that was disconnected in step 2.?


	NO

The VCC wires are not shorted to ground. Go to step 5.

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
	CKP sensor 3P connector: disconnected
	CMP sensor A 3P connector: disconnected
	CMP sensor B 3P connector: disconnected
	Output shaft (countershaft) speed sensor 3P connector: disconnected
	Fuel rail pressure sensor 5P connector: disconnected
	MAF sensor/IAT sensor 1 5P connector: disconnected
	MAP sensor/IAT sensor 2 4P connector: disconnected
	Rocker arm oil pressure sensor 3P connector: disconnected
	Turbocharger boost sensor 3P connector: disconnected
	Turbocharger 5P connector: disconnected
	Throttle body 6P connector: disconnected
	APP sensor 6P connector: disconnected
	Input shaft (mainshaft) speed sensor 3P connector: disconnected
	Neutral position sensor 4P connector: disconnected
	A/C pressure sensor 3P connector: disconnected
	FTP sensor 3P connector (KA/KC): disconnected
	PCM connector No. 1 (96P): disconnected
	PCM connector No. 2 (58P): disconnected

Connector	Terminal
PCM connector No. 1 (96P)	No. 61, No. 62, No. 63, No. 64, No. 65, No. 66, No. 67, No. 80, No. 81, No. 82, and No. 83
PCM connector No. 2 (58P)	No. 41, No. 46, No. 55, and No. 58

Is there any voltage?


	YES

Repair a short to power in the VCC wire(s) between PCM connector No. 1 terminals (No. 61, No. 62, No. 63, No. 64, No. 65, No. 66, No. 67, No. 80, No. 81, No. 82, and/or No. 83), PCM connector No. 2 terminals (No. 41, No. 46, No. 55, and/or No. 58) 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 PCM, then recheck. If DTC P0641 goes away and the PCM was substituted, replace the original PCM.?