What this code means
U1297 may indicate that the left side BSI radar unit is not receiving expected communication from the right side BSI radar unit over the B-CAN network.
What the vehicle may do
- Blind spot information functions may be limited or disabled.
- A warning message or indicator may appear depending on vehicle configuration.
- The fault may be intermittent if the communication or power condition comes and goes.
Possible fault areas
- Possible right side BSI radar unit power or ground issue.
- Possible right side BSI radar unit start-up issue.
- Possible B-CAN communication issue between the radar units.
Diagnostic path
Code overview
On this 2020 to 2025 Honda CR-V Hybrid, U1297 means the left side BSI radar unit has lost communication with the right side BSI radar unit. In plain terms, the left radar is expecting messages from the right radar over the B-CAN network and it is not seeing them the way it should. The vehicle may disable or limit blind spot information functions, and the fault area can be as simple as the right radar unit not powering up normally, a possible power or ground problem at that unit, or a possible communication issue on the B-CAN side. Start with that mindset before getting deep into network testing.
Start with the basic checks
Before chasing the code, start with the basic system checks and follow a structured diagnostic approach. Do not skip the simple checks just because this is a communication code. This code can set if the right side BSI radar unit does not start normally, so make sure the diagnosis begins with the right side unit and not just the left side unit that reported the loss of communication.
Check right side radar power and ground first
Next, check the power and ground circuit for the right side BSI radar unit first. That is the priority check for this code path. If the right side radar does not have the power and ground it needs, the left side radar will not receive its messages over B-CAN, and U1297 can be stored. Confirm that part of the circuit before moving farther into communication diagnostics.
Move into B-CAN communication diagnosis
After the right side radar power and ground checks are handled, continue with the B-CAN lost communication diagnostic path. Keep the focus on why the left side BSI radar unit cannot receive signals from the right side BSI radar unit over B-CAN. If the exact B-CAN path is not available in front of you, pause, recheck the earlier diagnostic path, and avoid guessing at parts or wiring repairs.
Confirmation step
For the confirmation step, turn the vehicle to the ON mode, then wait for at least 5 seconds. Keep this separate from the circuit testing. This is about giving the system time to wake up and communicate so you can see whether the fault returns under the required condition.
Takeaway
The clean way to handle U1297 is to start with the right side BSI radar unit power and ground, then continue into the B-CAN lost communication path if those checks do not explain the fault. Verify the repair and confirm the code stays gone without jumping to a radar unit replacement. For more diagnostic training, visit stepdiagnostics.com.
Final check
This code is best approached as a communication loss complaint: confirm the right side radar can power up correctly, then continue into the B-CAN communication path.
For more guided automotive diagnostics, visit STEP Diagnostics.
