Action Taken When the DTC Sets

WARNING: This page is about a different car, the 2017 GMC Acadia. However, it is still accessible from the selected car via links, so may be relevant.

DTC P1258 is a Type A DTC.
The engine will operate in the Overheated Engine Protection Operating Mode.
The IP will illuminate the coolant temperature indicator lamp and the driver information center (DIC), if equipped, may display a message.
If the protection mode is active and an ECT sensor DTC sets, the protection mode will remain active at the start of the next drive cycle until the ECT sensor DTC runs and passes.