Open Loop

When engine is first started and it is above 400 rpm, system goes into "open loop" operation. In "open loop", PCM/ECM ignores signal from 02S and calculates air fuel ratio based on inputs from ECT sensor and MAP sensor. The sensor stays in "open loop" until following conditions are met:

• The 02S sensor has a varying voltage output, showing that it is not enough to operate properly.
• The ECT sensor is above a specified temperature.
• A specific amount of time has elapsed after starting engine.