What this code means
U0146 may indicate that the PCM is not receiving the expected communication from the CAN gateway, or that the gateway information may be abnormal.
What the vehicle may do
- The vehicle may show communication-related warning indicators.
- Some module functions may behave abnormally when gateway communication is affected.
- The code may appear when the CAN gateway does not start normally.
Possible fault areas
- Possible CAN gateway startup issue
- Possible CAN gateway power or ground circuit issue
- Possible PF-CAN communication issue between the PCM and CAN gateway
Diagnostic path
Opening context
On this Civic, U0146 is a network communication code involving the PCM and the CAN gateway. In plain terms, the PCM may not be getting the gateway message it expects, or the message coming back may not look valid. The vehicle may have communication-related symptoms, warning indicators, or module functions that do not behave normally. Broadly, think in terms of a possible gateway startup issue, a possible PF-CAN communication problem, or a possible CAN gateway power or ground problem.
Start with the right checks
Before chasing the network side of this code, start with the basic system checks and follow a structured diagnostic approach. Also, do not skip the CAN gateway power and ground checks. This code may set if the CAN gateway does not start normally, and a power or ground circuit fault at the gateway can create the same kind of symptom.
What sets the code
The PCM sets U0146 when it cannot receive a signal from the CAN gateway over the PF-CAN line, or when the information sent from the CAN gateway is abnormal continuously for the specified cycle. So the diagnostic logic is not just whether a message exists; it is whether the PCM sees the expected gateway communication as valid and consistent.
Confirmation step
For the confirmation procedure, turn the vehicle to the ON mode, then wait 6 seconds. That gives the monitor its chance to see whether the gateway communication starts up and whether the PCM receives acceptable information.
Keep verification separate
After any checks or corrections, verify the repair and confirm the code stays gone under the same ON-mode confirmation condition. The key takeaway is simple: for U0146, confirm gateway startup, check gateway power and ground first, then evaluate the PCM-to-gateway communication path without guessing. For more diagnostic training, visit stepdiagnostics.com.
Final check
U0146 is approached as a communication and gateway startup diagnosis, with CAN gateway power and ground checked before deeper network troubleshooting.
For more guided automotive diagnostics, visit STEP Diagnostics.
