DTC P0030: O2 Sensor Heater Control Circuit (Bank 1, Sensor 1): Description

In order to control emissions of the CO, HC and NOx components of the exhaust gas, the heated oxygen sensor (HO2S), mounted before and after the catalytic converter, detects the oxygen content in the exhaust gas. The front HO2S signal is used to control air/fuel ratio (closed loop fuel control) and the rear HO2S signal is used to monitor front HO2S and catalyst for proper operation. The HO2S requires a minimum temperature to operate properly and provide closed loop fuel control. So HO2S contains a heater element to reduce its warming-up time and ensure its performance during all driving conditions. The ECM controls this heater element by duty cycle. The main relay supplies voltage to the heater and the ECM provides a ground circuit for activating the heater.