Circuit Description

Heated Oxygen Sensor (HO2S) bank, 2 sensor 1, monitors oxygen content in exhaust gasses before they enter into catalytic converter. ECM monitors this voltage and determines if exhaust is lean or rich and increases or decreases the injector pulse width.

DTC will set when signal from front oxygen sensor conflicts with reading from rear oxygen sensor. When DTC sets, MIL will illuminate after 2 consecutive ignition cycles in which diagnostic runs with active fault. ECM will record operating conditions at time of failure and store information in freeze frame buffer.