DTC P0125 - Excessive Time To Enter Closed Loop: Condition

WARNING: This page is about a different car, the 1997 Mazda Millenia. However, it is still accessible from the selected car via links, so may be relevant.

DTC is set when engine coolant temperature has not increased after engine is started and default period of time has passed with closed position switch in OFF position. Possible causes are:

Engine coolant temperature sensor malfunction.
Thermostat malfunction.
Engine cooling fan system malfunction.
Water pump malfunction.
Engine coolant passage clogged or leaks.
Engine coolant level or mixture incorrect.