Code P0125, Coolant Temp Sensor Closed Loop Minimum Temp Not Met: Notes

A closed loop air/fuel metering system is used to provide the best possible combination of driveability, fuel economy and emission control. Vehicle operates in open loop when first started, ignoring heated oxygen sensor signal and calculating air/fuel ratio based on inputs from engine coolant temperature, throttle position and mass air flow sensors only. When the following conditions are met, PCM will begin using heated oxygen sensor signal for controlling fuel delivery (closed loop).

• Heated Oxygen Sensor (HO2S No. 1) has varying voltage output indicating that it is hot enough for proper operation.
• ECT sensor indicates coolant temperature greater than 140°F (60°C).
• Time since start-up is at least 16 seconds for warm engine or 50 seconds for cold engine.

Code P0125 will set when the following condition is present.

• Engine coolant temperature sufficient to allow closed loop operation is not achieved within 9 minutes of start-up. Code P0125 does not illuminate the Malfunction Indicator Light (MIL).