What this code means
U1297 may mean the left side blind spot radar is not receiving expected communication from the right side blind spot radar over the B-CAN network.
What the vehicle may do
- The vehicle may display a blind spot system warning.
- Blind spot monitoring can be limited or unavailable.
- The code may return when the right side radar does not start normally.
Possible fault areas
- Possible B-CAN communication issue between the BSI radar units.
- Possible right side BSI radar power or ground circuit issue.
- Possible wiring or connector issue affecting radar communication.
- Possible radar unit startup issue.
Diagnostic path
Opening context
On this 2016 to 2024 Honda Civic with the 2.0 gas engine, U1297 is a BSI radar unit lost-communication code. In plain language, the left side blind spot radar may not be receiving the right side radar’s signals over the B-CAN network. The driver may see blind spot system warnings, and blind spot operation can be limited or unavailable. Broadly, this can involve B-CAN communication, wiring or connector issues, right side radar power or ground, or a right side radar unit that may not be starting normally.
Start clean and stay structured
Before getting deep into U1297, start with the basic system checks and keep the diagnostic path structured. Don’t jump straight to a radar unit. This code is about communication between the BSI radar units, so the first mindset is to prove whether the right side unit can power up and communicate, rather than guessing at parts.
Main diagnostic direction
The setting logic is straightforward: if the left side BSI radar unit cannot receive the right side BSI radar unit signals through B-CAN, the system decides there is an abnormality and stores U1297. If the right side BSI radar unit does not start normally, this code may also be stored. So the key checks stay around the right side radar’s ability to wake up and communicate, especially its power circuit and ground circuit.
Confirm the condition
To reproduce the operating condition, turn the vehicle to ON mode, then wait for at least 5 seconds. That gives the BSI radar communication check time to run before you decide whether U1297 is current or no longer returning.
Keep verification separate
After any correction, verify the repair separately from the circuit testing. Use the same confirmation approach: vehicle in ON mode, wait for at least 5 seconds, then confirm the code stays gone and the blind spot system behavior is back to normal.
Takeaway
Takeaway: U1297 points you toward a B-CAN communication problem involving the BSI radar units, with special attention on whether the right side radar is starting normally and has proper power and ground. Keep the diagnosis focused, confirm the monitor condition, and verify the code stays gone. For more diagnostic training, visit stepdiagnostics.com.
Final check
This diagnosis should stay focused on communication, startup, power, and ground for the right side BSI radar path.
For more guided automotive diagnostics, visit STEP Diagnostics.
