U05AC: Invalid Data Received From Vehicle Thermal Management Control Module

What it means

A receiving module detected implausible data from the vehicle thermal management module. Coolant loop coordination values fail plausibility checks and are rejected; sub-modules may revert to local control.

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 vehicle thermal management control module coordinates coolant-loop operation among systems such as the engine, battery, and cabin heating, depending on the vehicle. This code sets when another module rejects the thermal management module's coordination data as implausible, and connected systems may fall back to local control.

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. Save freeze-frame data and scan the thermal management, engine, battery, HVAC, and network modules for related codes.
2. Review live coolant-loop requests, temperatures, and reported operating states to identify values that are missing or inconsistent.
3. Inspect the thermal management module connectors, CAN wiring, coolant hoses, and visible connections for damage, corrosion, leaks, or loose fittings.
4. Check related temperature sensors, pumps, valves, and coolant-level faults that could make loop coordination data inconsistent.
5. Verify compatible software and configuration across the thermal management module, its submodules, and gateway, particularly after replacement.
6. If wiring and component inputs are sound, use manufacturer-approved network tests to isolate a thermal management controller, receiving-module, or gateway fault.

Common fixes

• Repair damaged connectors, grounds, or CAN wiring at the thermal management module.
• Repair coolant leaks or correct a confirmed pump, valve, or temperature-sensor fault affecting loop data.
• Correct software or configuration mismatches among the thermal management module, submodules, and gateway.
• Replace a thermal management module or gateway only after tests confirm the unit is faulty.

Can I keep driving?

If temperatures and vehicle operation are normal, keep trips short and monitor for warnings because loss of coordinated cooling can affect the engine, battery, or cabin systems. Stop if an overheating warning, battery temperature warning, or power reduction appears.