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U05B5 Invalid Data Received From Front Radar Module A

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Front radar modules measure distance and closing speed of objects ahead for adaptive cruise, emergency braking and lane change support. Mercedes-Benz documents this code on the 2026 CLA electric (series 174): the driver assistance controller N62/5 stores U05B555 when the front radar on the outer left delivers implausible data because it has not been configured. Bulletin LI54.71-P-080345 (versions of April and May 2026) ties it to a lasting warning that the assistance systems are unavailable, mainly on cars built before 5 September 2025, and calls for an N62/5 teach-in calibration or a calibration drive followed by at least seven minutes parked and locked. Other brands use letters differently, so A is not always a corner sensor. U02B4 means module A is silent; U05B6 is the right twin.

Likely causes

Radar sensor not configured or calibrated in the assistance controller (Mercedes N62/5)
Outdated software in the driver assistance controller
Radar knocked out of alignment after bumper damage or repair
Radar connector behind the bumper loose or wet

Symptoms

  • Driver assistance unavailable message that does not clear
  • Adaptive cruise and emergency braking switched off
  • Lane change or blind spot functions on the front left limited

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,800
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

front radar module a

Related codes

U02B4U05B6U05B7U05B8U0433

References: static.nhtsa.gov, static.nhtsa.gov, bosch-mobility.com.