Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC U1280: B-CAN Communication Bus Line Error (BUS-OFF) (MICU) (2018-19)
| DTC Description | DTC |
|---|---|
| U1280 B-CAN Communication Bus Line Error (BUS-OFF) |
DTC (MICU)
NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Refer to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks (2015-17), or Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks (2018-19) .
- Problem verification
-1. Clear the DTCs with the HDS.
- 2. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.
- 3. Wait for at least 6 seconds.
- 4. Check for DTCs with the HDS.
DTC Description DTC U1280 B-CAN Communication Bus Line Error (BUS-OFF) Is DTC U1280 indicated?
YES
Go to step 2.
NO
Intermittent failure, the system is OK at this time. Check for loose or poor connections.
- B-CAN related units check
-1. Turn the vehicle to the OFF (LOCK) mode.
- 2. Disconnect the appropriate connector at each control unit in the table one at a time. Clear the DTC, then recheck for DTCs after each unit is disconnected.
Control Unit Connector Gauge control module 32P connector Climate control unit Connector A (40P) Power window master switch 37P connector Automatic lighting control unit-sensor 5P connector Automatic lighting/rain sensor 5P connector Keyless access/TPMS control unit Connector C (20P) Parking and back-up sensor control unit 16P connector Power seat control unit Connector A (20P) Audio unit Connector A (24P) Audio-navigation unit Connector A (24P) Telematics control unit 36P connector Front seat heater control unit 14P connector Ventilated seat control unit 14P connector Left side BSI radar unit 6P connector Right side BSI radar unit 6P connector Multi View camera unit Connector A (20P) Wireless charger 7P connector DTC Description DTC U1280 B-CAN Communication Bus Line Error (BUS-OFF) Is DTC U1280 indicated with each individual unit disconnected?
YES
Leave the connectors disconnected, and go to step 3.
NO
Replace the control unit that was disconnected when DTC U1280 did not reset.
- Shorted wire check (B-CAN lines)
-1. Turn the vehicle to the OFF (LOCK) mode.
- 2. Disconnect the following connector.
Under-dash fuse/relay box connector M (12P) - 3. Check for continuity between test points 1 and 2 individually.
Test condition Vehicle OFF (LOCK) mode Under-dash fuse/relay box connector M (12P): disconnected
Test point 1 Under-dash fuse/relay box connector M (12P) No. 5 - Refer to: Under-Dash Fuse/Relay Box Connector For Inputs And Outputs (Without SH-AWD) (2015-17) or Under-Dash Fuse/Relay Box Connector For Inputs And Outputs (With SH-AWD) (2015-17) or Under-Dash Fuse/Relay Box Connector for Inputs and Outputs (2018-19) Test point 2 Body ground Test point 1 Under-dash fuse/relay box connector M (12P) No. 4 - Refer to: Under-Dash Fuse/Relay Box Connector For Inputs And Outputs (Without SH-AWD) (2015-17) or Under-Dash Fuse/Relay Box Connector For Inputs And Outputs (With SH-AWD) (2015-17) or Under-Dash Fuse/Relay Box Connector for Inputs and Outputs (2018-19) Test point 2 Body ground Is there continuity?
YES
Repair a short to ground in the B-CAN wires.
NO
Go to step 4.
- Shorted wire check (B-CAN_L to B-CAN_H line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Under-dash fuse/relay box connector M (12P): disconnected
Test point 1 Under-dash fuse/relay box connector M (12P) No. 5 - Refer to: Under-Dash Fuse/Relay Box Connector For Inputs And Outputs (Without SH-AWD) (2015-17) or Under-Dash Fuse/Relay Box Connector For Inputs And Outputs (With SH-AWD) (2015-17) or Under-Dash Fuse/Relay Box Connector for Inputs and Outputs (2018-19) Test point 2 Under-dash fuse/relay box connector M (12P) No. 4 - Refer to: Under-Dash Fuse/Relay Box Connector For Inputs And Outputs (Without SH-AWD) (2015-17) or Under-Dash Fuse/Relay Box Connector For Inputs And Outputs (With SH-AWD) (2015-17) or Under-Dash Fuse/Relay Box Connector for Inputs and Outputs (2018-19) Is there continuity?
YES
Repair a short in the B-CAN_L to B-CAN_H wire.
NO
The B-CAN_L to B-CAN_H wire is OK. Faulty MICU; replace the under-dash fuse/relay box .
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.