P0031

DTC P0031 O2 Sensor Heater Circuit Low Input (Bank1, Sensor1)

DESCRIPTION

In order to control the emission of the CO, HC and NOx components of the exhaust gas, a heated oxygen sensor (HO2S), mounted on the front side and rear side of 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 a closed loop fuel control system. So the HO2S contains a heater element to reduce warm-up time and ensure proper performance during all driving conditions, which allows for closed loop fuel control or catalyst monitoring immediately upon engine start-up. 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.

Detecting Condition & Limp Home:

DTC DETECTING CONDITION

1. DTC Description

ECM sets DTC P0031 if the ECM detects that the front HO2S heater control line is short to ground.

2. Conditions for Setting the DTC

Specification:

Schematic Diagram:

Signal Wave Form:

Step 1 - 3:

Step 4 - 5:

INSPECTION PROCEDURE