Circuit Description
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
This diagnostic monitors the time passed before Closed Loop fuel control occurs. The engine operates in Open Loop when first started. In Open Loop, the powertrain control module (PCM) ignores the oxygen sensor signal and calculates the air/fuel ratio based on inputs from the engine coolant temperature (ECT) sensor, the accelerator pedal position (APP) sensor, and the manifold absolute pressure (MAP) sensor. The PCM will begin Closed Loop fuel control when the oxygen sensor signal is active enough and the ECT sensor reaches a predetermined coolant temperature. If the PCM does not detect Closed Loop fuel control within a predetermined amount of time, this DTC sets.