Corroded, loose, or damaged electrical connector at the rear radar module B; Wiring harness damage between the rear radar module and the network gateway or control module; Failed rear radar module B due to internal fault or water intrusion; Low voltage or poor ground at the rear radar module, often from a weak battery or corroded ground point; Software incompatibility or missing calibration in the rear radar module after a replacement or update; Communication network fault, such as a shorted CAN bus or faulty termination resistor, affecting data from the rear radar module; Physical obstruction or misalignment of the rear radar sensor causing it to send invalid data

DTC codes / U05xx · Network communication / U05B8

U05B8Invalid Data Received From Rear Radar Module B

Q: What does code U05B8 mean?

Invalid Data Received From Rear Radar Module B. The U05B8 code indicates that a control module, typically the driver assistance or gateway module, has received invalid or missing data from the rear radar module B over the vehicle's communication network. The computer detected that the expected sensor messages were either absent, corrupted, or outside the acceptable data range, so it flagged the rear radar module as the source of the invalid data.

The U05B8 code indicates that a control module, typically the driver assistance or gateway module, has received invalid or missing data from the rear radar module B over the vehicle's communication network. The computer detected that the expected sensor messages were either absent, corrupted, or outside the acceptable data range, so it flagged the rear radar module as the source of the invalid data.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaNetwork communication

Symptoms you may notice

Rear cross-traffic alert or blind spot monitoring warning light illuminated on the dashboard
Driver assistance features such as lane change assist or rear collision warning become disabled
A message on the driver information center stating that rear radar or sensor is unavailable
Often no symptoms besides the warning light, with the vehicle driving normally
Intermittent operation of rear radar-based features, especially in wet or cold weather
Parking assist or rear automatic braking may stop functioning if the vehicle uses the same radar module

Common causes, most likely first

Corroded, loose, or damaged electrical connector at the rear radar module B
Wiring harness damage between the rear radar module and the network gateway or control module
Failed rear radar module B due to internal fault or water intrusion
Low voltage or poor ground at the rear radar module, often from a weak battery or corroded ground point
Software incompatibility or missing calibration in the rear radar module after a replacement or update
Communication network fault, such as a shorted CAN bus or faulty termination resistor, affecting data from the rear radar module
Physical obstruction or misalignment of the rear radar sensor causing it to send invalid data

How to diagnose and fix it

Inspect the rear radar module B connector and wiring for corrosion, moisture, or loose pins, and clean or repair as needed
Check battery voltage and ground connections at the rear radar module to ensure stable power supply
Use a scan tool to read live data and confirm whether the rear radar module is communicating and sending plausible values
Perform a network communication test to rule out a faulty CAN bus or gateway module affecting data from the rear radar module
If communication is present but data is invalid, check for software updates or recalibration procedures for the rear radar module
Replace the rear radar module B if internal failure is confirmed, then perform calibration and clear the code
Verify the repair by test-driving the vehicle and confirming that the U05B8 code does not return and that rear radar features operate correctly

What the rear radar data really means

A U05B8 code often appears after a low battery or jump-start event, because voltage dips can cause the rear radar module to send corrupted data that the network logs as invalid.
Many technicians replace the rear radar module only to find the real problem is a chafed wire in the rear bumper harness, so always perform a wiggle test on the harness while watching live data.
The code does not always mean the radar module is faulty; a faulty gateway module or a software glitch in another module can also cause it to report invalid data from the rear radar.
After replacing or disconnecting the rear radar module, a calibration drive is usually required, and skipping it can set U05B8 again even with a perfectly good module.
Rear radar module B is often shared with rear cross-traffic alert and blind spot monitoring, so a failure can disable multiple safety systems without any obvious driving symptom.

Can I keep driving with U05B8?

You can usually continue driving because the vehicle remains controllable, but rear cross-traffic alert and blind spot monitoring will be disabled, so rely on your mirrors and turn your head when reversing or changing lanes. Avoid towing or heavy loads that might obscure the rear sensors, and have the fault diagnosed soon to restore full driver assistance functionality.

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.