U02B4Lost Communication With Front Radar Module A
- Generic OBD-II code · Network
- How the car detects it
- At the front, radar modules measure range and speed of the traffic ahead, which adaptive cruise and automatic braking rely on; corner units also watch crossing traffic. U02B4 means module A no longer answers the assistance controller. No manufacturer documents U02B4 publicly, and letters differ by brand: on the 2026 Mercedes-Benz CLA electric (series 174) the invalid-data partner U05B555 shows that front radar A is the outer left unit, read by controller N62/5. GM uses its own code instead: its 2025 tables report a silent long-range radar as U0235 after 0.25 s, classed as emission-neutral Special Type C without lamp, and switch off adaptive cruise. U02B4 should behave alike: assistance messages, no MIL, normal engine operation. After a bumper repair or radar swap, calibration is often required.
- What you may notice
- Adaptive cruise and collision warning unavailable
- Driver assistance message in the cluster
- Likely causes
- LikelyRadar connector behind the bumper not latched, corroded or damaged after a collision
- PossibleSupply, ground or fuse of the radar interrupted
- PossibleRadar module failed
- RareLow battery voltage at start-up
- Repair
- Hard · Usually a job for a workshop.Typical cost: €50 – €1,800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.