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DTC codes / U05xx · Network communication / U05BF

U05BFInvalid Data Received From Trailer Backup Assist Control Module

U05BF is a communication fault indicating that a control module on the vehicle's network received data from the Trailer Backup Assist Control Module that failed its internal validity check. The receiving module detected that the message content, checksum, or signal timing did not match the expected format, so it flagged the data as invalid rather than acting on it.

SystemNetwork
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaNetwork communication

Symptoms you may notice

  • Trailer Backup Assist system is disabled or shows a fault message on the dashboard
  • Traction control or stability control warning light illuminated alongside the trailer assist warning
  • Backup camera or trailer guidance overlay fails to appear when reversing
  • Parking assist or rear cross-traffic alert features stop functioning
  • Often no symptoms besides the warning light, with the vehicle driving normally
  • Intermittent warning that appears only in damp weather or after a car wash

Common causes, most likely first

  1. Corroded or water-intruded electrical connector at the Trailer Backup Assist Control Module
  2. Damaged or chafed wiring in the harness running to the trailer backup assist module, often near the rear bumper or hitch area
  3. Failing Trailer Backup Assist Control Module internal circuitry producing corrupted CAN messages
  4. Low battery voltage or a weak charging system causing modules to brown out and transmit invalid data
  5. Poor ground connection shared by the trailer assist module and nearby body control electronics
  6. Aftermarket trailer wiring or hitch accessories backfeeding noise onto the CAN bus
  7. Software incompatibility or a failed module configuration after battery replacement or trailer wiring repair

How to diagnose and fix it

  1. Scan all modules for stored and pending codes, then record freeze-frame data for U05BF and any companion communication codes
  2. Inspect and clean the Trailer Backup Assist Control Module connector for corrosion, water intrusion, or bent pins
  3. Perform a voltage drop test on the module's power and ground circuits under load to rule out supply problems
  4. Check battery state of charge and charging system output, as low voltage corrupts module data
  5. Wiggle-test the harness between the module and the CAN bus junction while watching live data for dropouts
  6. Verify the module's software is current and reflash or reconfigure if a known calibration update applies
  7. If wiring and power are confirmed good, substitute a known-good Trailer Backup Assist Control Module and retest

What the invalid data flag really means

  • U05BF is set by the receiving module, not by the Trailer Backup Assist Control Module itself, so the faulty part is often the wiring or power supply rather than the module named in the code.
  • A weak battery or failing alternator is a commonly missed cause because the module can power up and communicate while still transmitting corrupted frames that fail the validity check.
  • Aftermarket trailer brake controllers and hitch wiring tapped into the rear harness frequently introduce noise or voltage spikes that corrupt trailer assist messages.
  • The code does not always mean the module has failed; a single intermittent connector fault in damp conditions can set it without any permanent hardware problem.
  • Clearing the code without checking freeze-frame data can send you chasing the wrong module, because the stored data shows which module flagged the fault and under what conditions.

Can I keep driving with U05BF?

The vehicle remains safe to drive because Trailer Backup Assist is a convenience feature, but avoid towing and reversing with a trailer until the fault is repaired since the system will not provide guidance. If stability control or other safety warnings appear alongside it, have the vehicle inspected promptly.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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