Circuit Description

To provide the best possible combination of driveability, fuel economy and emissions control a "closed loop" air/fuel metering system is used. When vehicle is first started PCM controls fuel delivery in "open loop mode", ignoring HO2S signals and calculates air/fuel ratio based on inputs from the ECT and TP sensors. DTC P0125 sets when a stuck open thermostat or other cooling system problem occurs, causing engine to not reach normal operating temperature is detected.