Network, generic

U045B Invalid Data Received From Anti-Lock Brake System (ABS) Control Module B

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

ABS module B is a second brake controller, found where braking has to survive a single fault. Bosch pairs an electromechanical booster or its integrated power brake with ESP for that purpose and, for automated driving, adds a separate redundant brake unit; its 2018 show message was that automated driving needs redundancy. U045B is stored when the partner, often the main brake unit or the automated driving computer, receives status or wheel data from B but rejects them because counters, checksums or values do not fit; U015A means B is silent, U0415 concerns the main ABS module. No manufacturer documents U045B publicly. Normal braking usually remains through the other path, yet a brake warning may appear and anything that relies on redundancy, such as automated or hands-off driving, is blocked.

Likely causes

Software levels of brake module A and B or the automation computer not matching
Weak supply or ground of brake module B
Internal fault of brake module B

Symptoms

  • Brake system or ABS warning
  • Automated or hands-off driving functions unavailable

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–1,500
Time0.5–3 h

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

Parts involved

abs module b

Related codes

U015AU0415U0121U045C

References: bosch-mobility.com, us.bosch-press.com, autosar.org.