U0456 Invalid Coolant Temp Module Data
The U0456 code indicates that the powertrain control module (PCM) or engine control module (ECM) has received invalid, corrupted, or missing data from the Coolant Temperature Control Module over the CAN bus. This module manages advanced thermal system components such as the electronic thermostat valve, electric water pump speed, or coolant flow. The fault is not with the temperature sensor itself but with data communication or integrity from the dedicated coolant temperature control module.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Internal failure of the Coolant Temperature Control Module
- CAN bus wiring issues: short, open circuit, or incorrect resistance
- Faulty master control module (PCM/ECU) interpreting the data
- Corrosion or excessive resistance in the coolant temperature control module connectors
- Outdated or corrupted software in the coolant temperature control module
- Faulty CAN bus termination resistor
3. Symptoms You Will Notice
- Check Engine Light illuminated
- Possible engine overheating or improper warm-up
- Reduced engine performance or fuel economy
- Electric cooling fan running continuously or not at all
4. Step-by-Step Diagnosis
Scan for all stored codes and freeze frame data
Inspect CAN bus wiring and connectors for damage, corrosion, or loose connections
Check resistance and termination on the CAN bus
Test the Coolant Temperature Control Module power and ground circuits
Attempt to communicate with the module via scan tool; if no response, suspect module failure
Update module software if applicable
Replace the Coolant Temperature Control Module if all other checks pass
5. Frequently Asked Questions
Is it safe to drive?▼
You can usually drive short distances, but the vehicle may experience cooling system issues. It's best to diagnose and repair promptly to avoid engine damage from overheating.
How much does it cost to fix?▼
Diagnosis typically costs $100-$150. Repair costs vary: wiring repairs $100-$300, module replacement $200-$600, plus labor. Total can range from $200 to $800.