DTC Advanced Diagnostics: U0146 (K20C2) - Honda Civic FC/FK 2016-2021

DTC Advanced Diagnostics: U0146

DTC U0146: F-CAN Malfunction (Powertrain Control Module (PCM)-CAN Gateway)

General Description

The controller area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using two signal lines (F-CAN_H and F-CAN_L). When the information is not sent from the CAN gateway via the F-CAN lines and this condition continues for a specified time or when the information sent from the CAN gateway is abnormal and this condition continues for a specified cycle, the powertrain control module (PCM) detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type

Execution	Continuous
Sequence	None
Duration	1 second or more
DTC Type	One drive cycle, MIL on

Enable Conditions

Condition	Minimum	Maximum
Elapsed time after the vehicle condition is turned to the ON mode	3 seconds	–
12 volt battery voltage [Battery]	10.0 V	–

[ ]: HDS Parameter

Malfunction Threshold

Either of the condition is met:

	The PCM cannot receive any signals from the CAN gateway via the F-CAN lines for at least 1 second.
	The information sent from the CAN gateway is abnormal at least 20 times.

Possible Cause

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

	F-CAN circuit F-CAN A_H line open
	F-CAN circuit F-CAN A_L line open
	F-CAN circuit F-CAN A_H line short to ground
	F-CAN circuit F-CAN A_L line short to ground
	F-CAN circuit F-CAN B_H line open
	F-CAN circuit F-CAN B_L line open
	F-CAN circuit F-CAN B_H line short to ground
	F-CAN circuit F-CAN B_L line short to ground
	CAN gateway failure (include fuse blown)
	PCM internal circuit failure

Diagnosis Details

Conditions for setting the DTC

When a malfunction is detected, the MIL comes on and a Pending DTC, a Confirmed DTC, the freeze data, and the on-board snapshot are stored in the PCM memory.

Conditions for clearing the DTC

The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, the freeze data, and the on-board snapshot can be cleared with the scan tool clear command or by disconnecting the 12 volt battery.