What this code means
U1297 may indicate that the left side BSI radar unit is not receiving the right side BSI radar unit signal over the B-CAN network.
What the vehicle may do
- The vehicle may display blind spot or driver assist related warnings.
- The blind spot information function may be limited or may not operate normally.
Possible fault areas
- Possible right side BSI radar unit power or ground circuit trouble.
- Possible right side BSI radar unit startup issue.
- Possible B-CAN communication path concern between the radar units.
Diagnostic path
Opening context
On this 2018 to 2025 Honda Accord Hybrid, U1297 is a communication fault involving the BSI radar units. In plain terms, the left side BSI radar unit may not be seeing the right side BSI radar unit on the B-CAN network. The vehicle may show blind spot system warnings or the driver assist feature may not operate normally. The broad areas to keep in mind are right side radar power and ground, the radar unit starting up correctly, and possible B-CAN communication trouble. Start with the basic system checks so you know the vehicle, battery state, connectors, and scan tool information are not leading you in the wrong direction.
Why the code sets
The logic for U1297 is straightforward: if the left side BSI radar unit cannot receive signals from the right side BSI radar unit through B-CAN, it decides there is an abnormal condition and stores the code. So do not treat this as only a left side radar problem. The missing signal is from the right side radar unit, and the network path between the units matters.
First diagnostic priority
Before going deeper into the communication diagnosis, check the power and ground circuit for the right side BSI radar unit first. That is the first practical split in this diagnosis because the code may set if the right side radar unit does not start normally, and it may also set from a power or ground circuit failure at that unit.
Network direction
After the right side radar power and ground have been checked, treat the remaining path as a B-CAN lost communication problem. Stay disciplined here: if the communication path points outside the radar unit, pause, recheck the earlier diagnostic path, and avoid guessing. The important point is to prove whether the right side radar is powered up and able to communicate before making any call on the unit itself.
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 the operating check used to let the system run its communication check again and see whether U1297 comes back.
Verification and takeaway
Once the fault path has been addressed, verify the repair and confirm the code stays gone under the same basic operating condition. The takeaway on U1297 is simple: the left BSI radar is complaining because it is not receiving the right BSI radar signal over B-CAN, so start with right side radar power and ground, then work the communication path in order. For more diagnostic training, visit stepdiagnostics.com.
Final check
U1297 is often approached by confirming the right side radar can power up correctly, then following the B-CAN communication path without guessing.
For more guided automotive diagnostics, visit STEP Diagnostics.
