General Information

Component Location





General Description

When the engine is first started, the fuel control system operates in an open loop operation, ignoring the HO2S (Heated Oxygen Sensor) signal and calculating the air/fuel ratio based on inputs from the engine coolant temperature, the throttle position and the mass air flow sensors. The ECM will begin by using the oxygen sensor signal for controlling the fuel delivery (closed loop) when the following conditions are met:
- The engine has run a minimum amount of time at engine start up.
- The HO2S has a varying voltage output showing that it is hot enough to operate properly.
- The ECT has increased a minimum amount based on the ECT at start up.
The ECM monitors the amount of time for the cooling system to achieve closed loop operating temperature. The engine coolant temperature sufficient to allow closed loop operation is not achieved within a predetermined time frame, ECM sets DTC.

DTC Description

The purpose of this diagnosis is to monitor the minimum coolant temperature that enables lambda closed loop control after start. Minimum coolant temperature to run lambda control must be reached before the threshold time predetermined. If the lambda control is not active because of low engine coolant temperature within predetermined minimum time after start, the ECM sets DTC P0125

DTC Detecting Condition





Specification

[ECT sensor]





[THERMOSTAT]






Schematic Diagram