U045C: Invalid Data Received From Power Steering Control Module B

What it means

A receiving module detected implausible data from power steering control module B. Steer-assist torque or motor current values fail plausibility checks and are rejected; assist may reduce or fail to a fail-safe map.

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 power steering control module B, which reports steering-assist information such as torque or motor current. U045C sets when those values fail plausibility checks and the receiving module rejects them, potentially causing assist to be reduced or switched to a fail-safe setting.

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. Scan all modules, save freeze-frame data, and identify which module logged U045C along with any steering, voltage, or communication codes.
2. Check live steering-assist torque and motor-current data from power steering control module B for readings that are implausible, erratic, or inconsistent with steering input.
3. Inspect module B's connectors, power and ground connections, and wiring for damage, corrosion, loose terminals, or signs of water intrusion.
4. Check whether a recent module replacement or software update preceded the fault, and verify that module B has the correct vehicle configuration and software.
5. If the reported values remain implausible, check CAN communication and gateway routing, then test module B and its sensor inputs using the manufacturer's diagnostic procedure.

Common fixes

• Repair a loose or damaged connector, power connection, ground, or wiring serving power steering module B.
• Correct a configuration or software mismatch after module replacement or an update.
• Repair a faulty steering sensor input or its circuit if testing confirms the fault.
• Repair CAN wiring or gateway routing that is corrupting module B messages.
• Replace power steering control module B if its internal fault is confirmed.

Can I keep driving?

Steering assist may become weak or unpredictable, especially at low speeds, so avoid unnecessary driving and do not rely on the vehicle if steering effort changes suddenly. Arrange prompt diagnosis; stop safely if you cannot steer with confidence.