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

What it means

A receiving module detected implausible data from ABS control module B (typically secondary brake controller in twin-system architectures). Wheel-speed, slip or pressure values fail plausibility checks and are rejected.

At a glance

• Usually lights the warning light of the system that lost communication
• The engine or gearbox may go into limp mode

How it works

The receiving module checks messages from ABS control module B, which may be the secondary brake controller in a twin-system design. This code sets when reported wheel-speed, brake-slip, or pressure data fails plausibility checks and is rejected.

Common causes

Most likely first.

1. Module internal fault or sensor input drift
2. Software version mismatch after replacement
3. 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

1. Use a scan tool to record freeze-frame details and identify which module set U045B, then scan all modules for related ABS and communication codes.
2. Compare live wheel-speed, slip, and brake-pressure data attributed to ABS control module B with other available readings and check for values that jump or conflict.
3. Inspect the ABS control module B connector, wiring, grounds, and any related sensor connections for looseness, corrosion, damage, or water intrusion.
4. Check whether the fault began after a module replacement or software update and verify that ABS module B has the correct configuration and software for the vehicle.
5. If the data remains implausible, have the CAN network and gateway message routing checked, then test ABS module B and its sensor inputs against the manufacturer's diagnostic procedure.

Common fixes

• Repair a loose, corroded, or damaged ABS module B connector or wiring.
• Correct the ABS module B configuration or software mismatch after replacement or an update.
• Repair a faulty sensor input or its circuit if testing identifies one.
• Repair gateway routing or CAN network faults affecting ABS module B messages.
• Replace ABS control module B if its internal fault is confirmed.

Can I keep driving?

Because this fault concerns ABS data, braking assistance or stability functions may be limited, and other systems may enter a fail-safe mode. Drive cautiously only if normal braking is intact; avoid hard braking and have the fault checked promptly, and stop if braking behavior changes.