P0125 - Insufficient Coolant Temp For Closed Loop Fuel Control

The Engine Coolant Temperature (ECT) sensor circuit is monitored by the Powertrain Control Module (PCM). The test fails when the ECT sensor signal is not practical even when some time has passed after starting the engine or the engine coolant temperature is insufficient for closed loop fuel control.

Possible Causes:
^ High resistance in the ECT sensor circuit
^ Damaged ECT sensor
^ The cooling system thermostat
^ Low coolant level

Diagnostic Aids:
Disconnect the ECT sensor circuit connector, insert a jumper between the SIG RTN terminal and the ECT sensor signal terminal at the harness connector with the key ON and engine OFF, the ECT PID should read approximately 100°C (212°F).