Possible causes

– Low engine coolant level
– Leaking or stuck open thermostat
– Faulty Engine Coolant Temperature (ECT) sensor
– Engine Coolant Temperature (ECT) sensor harness is open or shorted
– Engine Coolant Temperature (ECT) sensor electrical circuit poor connection

When is the code detected?

The voltage sent to Powertrain Control Module (PCM) from the Engine Coolant Temperature (ECT) sensor is not practical, even when some time has passed after starting the engine. The engine is taking too long to reach the normal temperature level.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0125 PONTIAC Description

The Powertrain Control Module (PCM) monitors the Engine Coolant Temperature (ECT) sensor in order to determine how long it takes the engine to reach the coolant temperature required for Closed Loop operation. Detected Trouble Code (DTC) P0125 sets if the PCM determines that the engine does not reach Closed Loop temperature in a specified amount of time. This test will not run if either the intake air or engine coolant temperature is too low at start-up. The PCM will only run this DTC on a cold start and only once per cold start.