Damaged or corroded wiring or connector pins at the ABS control module B harness; Faulty ABS control module B internal circuitry causing it to output invalid data; Low or unstable battery voltage affecting module communication; CAN bus communication line fault (open, short, or excessive resistance) between modules; Poor ground connection for the ABS control module B; Aftermarket electronic accessories improperly wired into the CAN network; Software or calibration issue in the ABS module requiring reprogramming

DTC codes / U04xx · Invalid data received from a module / U045B

U045BInvalid Data Received From Anti-Lock Brake System (ABS) Control Module B

U045B is a communication fault where the primary computer (often the engine or body control module) receives data from the anti-lock brake system (ABS) control module B that it considers invalid or corrupted. The computer detects that the messages are present but fail plausibility or checksum tests, so it cannot trust the ABS data for functions like stability control or speed reporting.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaInvalid data received from a module

Symptoms you may notice

Anti-lock brake system (ABS) warning light illuminated on the dashboard
Traction control or stability control warning light also on, since these systems share ABS data
Speedometer may read erratically or drop to zero if vehicle speed is derived from ABS
Cruise control may become inoperative or disengage unexpectedly
Often no symptoms besides the warning light, with brakes functioning normally
Transmission may shift harshly or hold gears if speed data is used for shift scheduling

Common causes, most likely first

Damaged or corroded wiring or connector pins at the ABS control module B harness
Faulty ABS control module B internal circuitry causing it to output invalid data
Low or unstable battery voltage affecting module communication
CAN bus communication line fault (open, short, or excessive resistance) between modules
Poor ground connection for the ABS control module B
Aftermarket electronic accessories improperly wired into the CAN network
Software or calibration issue in the ABS module requiring reprogramming

How to diagnose and fix it

Connect a scan tool and record all stored codes in every module, then clear codes and test-drive to see if U045B returns
Inspect the ABS control module B connectors and harness for corrosion, loose pins, or chafed wires
Check battery voltage and charging system output, as low voltage can cause invalid data flags
Perform a voltage drop test on the ABS module B power and ground circuits
Use an oscilloscope or CAN analyzer to check signal integrity on the communication bus
If wiring and power are good, reprogram or replace the ABS control module B and perform any required calibration

Why U045B Is Often a Wiring Issue

A common misdiagnosis is replacing the ABS module when the real fault is a corroded connector pin or chafed wire that intermittently corrupts data.
U045B can be set by a weak battery or poor ground even if the ABS module itself is healthy, so always verify power and ground integrity first.
The code does not always mean the ABS module is bad; it can be triggered by another module on the bus transmitting invalid data that the ABS module repeats.
Aftermarket alarms, remote starters, or phone chargers plugged into the data link connector can introduce noise and set invalid data codes.
Some vehicles require a relearn or calibration procedure after battery replacement or module swap, and skipping it can leave U045B stored.

Can I keep driving with U045B?

The vehicle is generally safe to drive because the base brakes still work, but avoid relying on anti-lock braking or stability control, and do not tow or drive in slippery conditions until the fault is repaired.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.