U02B6: Lost Communication With Rear Radar Module A

What it means

The vehicle bus reports loss of communication with rear radar module A. Blind-spot warning, lane-change assist and rear cross-traffic alert dependent on this sensor are inhibited.

How it works

Rear radar module A supplies distance and object data for the driver-assistance functions assigned to that radar. The vehicle network monitors messages from module A and sets this code when they stop arriving or cannot be understood. The affected blind-spot, lane-change or rear cross-traffic functions may then be disabled.

Common causes

Most likely first.

1. Bus wiring open or shorted
2. Module without power or ground
3. Module failed

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

1. Scan all modules and save freeze-frame or event data to see when communication with rear radar module A was lost and whether other network faults appeared at the same time.
2. Check the vehicle display and live scan data to identify which rear radar functions are unavailable and whether module A responds intermittently.
3. Inspect module A's connector and nearby bus wiring for looseness, corrosion, water entry, impact damage or pinched wires.
4. Check the specified power and ground at module A under the conditions in the manufacturer's service information, since a missing supply can make a sound module appear offline.
5. Test the bus wiring to module A for opens, shorts and connection faults using the manufacturer's network test procedure.
6. If wiring, power and ground pass, use the manufacturer's diagnostic procedure to assess module A and verify communication after repair.

Common fixes

• Reconnect or repair a loose, corroded or damaged connector at rear radar module A.
• Repair an open or short in the bus wiring serving module A.
• Restore module A's power or ground by repairing the affected supply wiring or connection.
• Replace or reprogram rear radar module A only if the required diagnostic checks identify it as faulty.

Can I keep driving?

You can usually drive cautiously, but do not rely on the blind-spot, lane-change or rear cross-traffic features that depend on module A. Check mirrors and surroundings directly, and avoid relying on those alerts when reversing or changing lanes.