What it means
A receiving module detected implausible data from front radar module B. Distance/closing-speed values fail plausibility checks against camera/lidar and are rejected; ACC, AEB and FCW degrade.
At a glance
- Usually lights the warning light of the system that lost communication
How it works
Front radar module B measures distance and closing speed ahead and shares those values with driver-assistance systems. This code sets when a receiving module finds module B's data implausible compared with other vehicle inputs and rejects it, potentially limiting adaptive cruise control, automatic emergency braking, or forward collision warning.
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
- Scan all modules and save freeze-frame data to identify which module rejected front radar B's data and which assistance systems reported related faults.
- Check for warnings or messages showing that adaptive cruise control, automatic emergency braking, or forward collision warning is limited.
- Inspect the front radar B sensor area for dirt, ice, damage, a shifted mounting position, or an accessory blocking its view.
- Inspect radar B's connectors and accessible wiring for looseness, impact damage, corrosion, or water intrusion.
- Use a scan tool to compare radar B distance and closing-speed data with the vehicle's other available sensor data, and check for related CAN or gateway faults.
- If radar B, the bumper, or a related module was replaced or disturbed, verify software configuration and required aiming or calibration.
Common fixes
- Remove dirt, ice, or other obstruction from the front radar B area.
- Repair damaged or poorly connected radar wiring or connectors.
- Correct gateway routing or network configuration if radar B messages are being mishandled.
- Update or configure a replacement module to the required software version.
- Restore the radar's mounting and calibration, or replace it if an internal fault is confirmed.
Can I keep driving?
Drive without relying on adaptive cruise control, automatic emergency braking, or forward collision warning if the vehicle reports them unavailable. Leave extra following distance and be prepared to brake yourself; these safety features may not intervene.
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.