U0456: Invalid Data Received From Coolant Temperature Control Module

What it means

A receiving module detected implausible data from the coolant temperature (electric thermostat) control module. Temperature setpoint vs. actual values fail plausibility checks and are rejected.

At a glance

• Usually lights the warning light of the system that lost communication
• Affects emissions; the car can fail an emissions test

How it works

The coolant temperature control module manages an electronically controlled thermostat and reports temperature-related information to other modules. U0456 is set when a receiving module finds the reported setpoint or actual-temperature relationship implausible and rejects the data; this is a data-validity fault, not by itself proof that the engine is overheating.

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 engine and cooling-system modules for U0456 and related temperature or thermostat codes, saving freeze-frame data and coolant readings before clearing them.
2. With the engine cold, compare scan-tool coolant temperature readings with ambient conditions and check whether the values change smoothly as the engine warms.
3. Inspect the coolant temperature control module, thermostat connector, and visible wiring for damage, corrosion, loose connections, or coolant contamination.
4. Check coolant level and look for leaks, while avoiding opening the cooling system when hot.
5. Use scan data or the manufacturer's specified test procedure to compare the commanded thermostat setpoint with actual reported temperature.
6. If the module or a communicating control unit was replaced or updated, verify software compatibility and configuration, then test the module and network as specified.

Common fixes

• Repair a loose, corroded, or damaged thermostat-control connector or wiring.
• Correct module software or configuration incompatibility after replacement or programming.
• Repair a coolant leak or other condition that is distorting temperature readings.
• Replace a faulty temperature sensor, electronically controlled thermostat, or control module only after testing identifies it.

Can I keep driving?

If the temperature gauge rises, a coolant warning appears, or the engine runs unusually hot, stop safely and let it cool; overheating can cause severe engine damage. Otherwise, arrange diagnosis soon because incorrect temperature data can affect engine control and emissions.