What it means
A receiving module detected implausible data from the trailer backup assist module. Hitch angle or trajectory values fail plausibility checks and are rejected.
How it works
The trailer backup assist module calculates trailer angle and steering trajectory from the vehicle’s inputs and reports them over the vehicle network. A receiving module sets U05BF when those values from the trailer backup assist module fail its plausibility checks and are rejected.
Common causes
Most likely first.
- Module internal fault or sensor input drift
- Software version mismatch after replacement
- Gateway module routing CAN messages incorrectly
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
How to diagnose it
- Use a scan tool to record freeze-frame data and identify which module stored U05BF, along with any related network or trailer-assist codes.
- Check whether trailer backup assist is available and note any warnings or incorrect hitch-angle or trajectory display.
- Inspect the trailer backup assist module’s connectors, power and ground connections, and network wiring for looseness, corrosion, damage, or poor repairs.
- Compare live trailer angle and trajectory data with the trailer and steering inputs while stationary, following the vehicle’s service information.
- If the module or gateway was recently replaced or updated, verify compatible software and configuration, then check network message routing and module faults using vehicle-specific service information.
Common fixes
- Repair a loose, corroded, or damaged trailer-assist connector or network wire.
- Restore the module’s specified power or ground connection.
- Correct module software or configuration incompatibility after replacement.
- Diagnose or replace a faulty trailer backup assist module if its inputs or reported data remain implausible.
- Repair gateway routing or network faults if other modules also report invalid or missing messages.
Can I keep driving?
If the vehicle steers and brakes normally, drive cautiously without relying on trailer backup assist; use a spotter when reversing with a trailer. Stop using the feature if its guidance is erratic, and address any additional vehicle warnings promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.