OBD-II code U0456 indicates that a receiving module (typically the PCM) has detected invalid data from the Coolant Temperature Control Module. This is a network communication fault, meaning the data sent by the coolant temperature module is corrupted, intermittent, or out of expected range.
The module itself may have an internal failure, causing it to send incorrect or corrupted data on the communication bus.
Chafed, broken, or corroded wiring and loose or damaged connectors between the coolant temperature control module and the network can interrupt or distort data transmission.
A high-resistance or corroded ground at the coolant temperature control module can cause erratic module operation and invalid data output.
Outdated or mismatched software in the PCM or coolant temperature control module may lead to misinterpretation of data, triggering the code.
In rare cases, the receiving module (PCM) may have an internal fault causing it to incorrectly flag valid data as invalid. This should only be considered after all other causes are ruled out.
It means the Powertrain Control Module (PCM) or another receiving module has detected invalid data from the Coolant Temperature Control Module over the vehicle's communication network.
It may be possible to drive, but the vehicle could experience poor performance, overheating, or cooling fan issues. It's best to diagnose and repair promptly to avoid engine damage.
Almost never. The PCM is the receiver of the invalid data, not the source. The problem is usually with the coolant temperature control module, wiring, or connections. Replacing the PCM should be a last resort after all other possibilities are exhausted.
Common symptoms include an inoperative or erratic temperature gauge, cooling fans running constantly or not at all, poor fuel economy, and possible engine overheating or hard starting.