DTC U0146 (2016 2017 2018 PGM-FI System (With CAN Gateway))

DTC U0146  : F-CAN Malfunction (PCM-CAN Gateway)

NOTE: Before you troubleshoot, review the general troubleshooting information - Refer to: How to Troubleshoot the Fuel and Emissions Systems, or How to Troubleshoot the Brake Booster Pressure Monitoring System (2016 2017 2018 2019 2020), or How to Troubleshoot the Fuel and Emissions Systems(With Auto Idle Stop System) (2016) .
• According to the detected DTC(s), check for the power circuit and the ground circuit of the control unit which cannot communicate with the PCM.

DTC (PGM-FI)

1. 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	Freeze Frame
   U0146 F-CAN Malfunction (PCM-CAN Gateway)

   Is DTC U0146 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 CAN gateway and the PCM.

2. CAN gateway system DTC check

   -1. Turn the vehicle to the ON mode.

   - 2. Check for CAN gateway system DTCs with the HDS.

   DTC Description	DTC

   Are any DTCs indicated?

   YES 

   Go to the troubleshooting for CAN gateway system DTC(s) .

   NO 

   Go to step 3.

3. F-CAN circuit communication check

   -1. Select the FUNCTION TEST in the CAN gateway with the HDS, then select the F-CAN Bus Connected Unit Check.

   F-CAN Bus Connected Unit Check

   Which result is indicated?

   PCM (Bus A) is Not Available

   Go to step 4.

   PCM (Bus B) is Not Available

   Go to step 6.

4. Open wire check (F-CAN A_H line)

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

   - 2. Jump the SCS line with the HDS.

   - 3. Disconnect the following connectors.

   CAN gateway 24P connector

   PCM connector A (51P)

   - 4. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	CAN gateway 24P connector: disconnected
   	PCM connector A (51P): disconnected
   Test point 1	CAN gateway 24P connector No. 14
   Test point 2	PCM connector A (51P) No. 9 - Refer to: PCM Connector for Inputs and Outputs (2016), or PCM Connector for Inputs and Outputs (2017 2018 2019 2020)

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The F-CAN A_H wire is OK. Go to step 5.

   NO 

   Repair an open in the F-CAN A_H wire between the PCM (A9) and the CAN gateway.

5. Open wire check (F-CAN A_L line)

   -1. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	CAN gateway 24P connector: disconnected
   	PCM connector A (51P): disconnected
   Test point 1	CAN gateway 24P connector No. 15
   Test point 2	PCM connector A (51P) No. 10 - Refer to: PCM Connector for Inputs and Outputs (2014 2015), or PCM Connector for Inputs and Outputs (2016), or PCM Connector for Inputs and Outputs (2017 2018 2019 2020)

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The F-CAN A_L wire is OK. Check for poor connections or loose terminals at the CAN gateway and the PCM. Update the PCM if it does not have the latest software, or substitute a known-good PCM - Refer to: PCM Removal and Installation (2016 2017 2018 2019 2020) , then recheck. If DTC U0146 goes away and the PCM was updated, troubleshooting is complete. If DTC U0146 goes away and the PCM was substituted, replace the original PCM - Refer to: PCM Removal and Installation (2016 2017 2018 2019 2020) .

   NO 

   Repair an open in the F-CAN A_L wire between the PCM (A10) and the CAN gateway.

6. Open wire check (F-CAN B_H line)

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

   - 2. Jump the SCS line with the HDS.

   - 3. Disconnect the following connectors.

   CAN gateway 24P connector

   PCM connector A (51P)

   - 4. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	CAN gateway 24P connector: disconnected
   	PCM connector A (51P): disconnected
   Test point 1	CAN gateway 24P connector No. 11
   Test point 2	PCM connector A (51P) No. 11 - Refer to: PCM Connector for Inputs and Outputs (2016), or PCM Connector for Inputs and Outputs (2017 2018 2019 2020)

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The F-CAN B_H wire is OK. Go to step 7.

   NO 

   Repair an open in the F-CAN B_H wire between the PCM (A11) and the CAN gateway.

7. Open wire check (F-CAN B_L line)

   -1. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	CAN gateway 24P connector: disconnected
   	PCM connector A (51P): disconnected
   Test point 1	CAN gateway 24P connector No. 10
   Test point 2	PCM connector A (51P) No. 12 - Refer to: PCM Connector for Inputs and Outputs (2016), or PCM Connector for Inputs and Outputs (2017 2018 2019 2020)

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The F-CAN B_L wire is OK. Check for poor connections or loose terminals at the CAN gateway and the PCM. Update the PCM if it does not have the latest software, or substitute a known-good PCM - Refer to: PCM Removal and Installation (2016 2017 2018 2019 2020) , then recheck. If DTC U0146 goes away and the PCM was updated, troubleshooting is complete. If DTC U0146 goes away and the PCM was substituted, replace the original PCM - Refer to: PCM Removal and Installation (2016 2017 2018 2019 2020) .

   NO 

   Repair an open in the F-CAN B_L wire between the PCM (A12) and the CAN gateway.