What this code means
U0146 may indicate a communication problem between the PCM and the CAN gateway.
What the vehicle may do
- The vehicle may show communication-related warning behavior.
- Scan-tool communication or module data may be incomplete or abnormal.
- Some systems can act differently if gateway communication is not normal.
Possible fault areas
- CAN gateway startup
- CAN gateway power or ground
- Network communication path between the CAN gateway and PCM
Diagnostic path
Open on what U0146 means
On this Accord Hybrid, U0146 is a network communication code between the PCM and the CAN gateway. In plain language, the PCM may not be getting a usable message from the gateway, or the gateway information may be abnormal. The vehicle may have communication-related warning behavior, limited module communication, or scan-tool data that does not line up normally. Broadly, the possible fault areas can include the CAN gateway waking up correctly, its power and ground, or the network path between the gateway and the PCM.
Understand the setting logic
The fault logic is straightforward: if the PCM cannot receive the signal from the CAN gateway over the PF-CAN M line or the PD-CAN N line, or if the information coming from the gateway is abnormal for the required cycle, the PCM stores U0146. So do not treat this as a random module code. Work it like a communication fault, and first make sure the gateway itself can start up normally.
Start with the basic checks, then gateway power and ground
Before troubleshooting, start by reviewing the basic troubleshooting approach for this system, so you are not chasing a network code without the usual checks. Then, before getting deep into network testing, check the CAN gateway power and ground circuit first. That matters here because this code may set if the gateway does not start normally, and a gateway power or ground problem can make the PCM see a lost or abnormal communication condition even when the bus wiring itself is not the first problem.
Move into the communication path carefully
After the gateway power and ground side has been handled, the diagnostic direction moves into the lost-communication path for the F-CAN bus connection to the CAN gateway. The detailed bus test steps are not available in this path, so this is the point where you should pause, recheck the earlier diagnostic path, and avoid guessing at connector, circuit, or module conclusions without the actual network test flow in front of you.
Confirmation and close
For the confirmation step that is given, turn the vehicle to the ON mode and wait 6 seconds. Keep that separate from the category-specific testing: first prove the gateway can power up and communicate, then verify the repair and confirm the code stays gone. Takeaway: U0146 is a PCM-to-CAN-gateway communication fault, so start with gateway power and ground, then follow the lost-communication path without jumping to parts. For more diagnostic training, visit stepdiagnostics.com.
Final check
U0146 should often be approached as a gateway communication problem: confirm the gateway can wake up and has good power and ground before moving deeper into network testing.
For more guided automotive diagnostics, visit STEP Diagnostics.
