General Information

Engine Control
P0031 HO2S Heater Control Circuit Low (Bank 1 / Sensor 1) - General Information

Component Location





General Description

Lambda sensor installed at exhaust manifold is planar ZrO2 dual cell type and it senses O2 density of exhaust gas for accurate EGR control through fuel correction. It also limits smoke which is generated by reach air-fuel mixture at engine maximum loading condition. ECM controls pumping current in order to fit lamda-value from linear O2 sensor to 1.0.
Lean air-fuel mixture(1.0Rich air-fuel mixture(0.9This performance is the most active and fast at normal operating temp.(450°C~600°C) thus, in order to reach normal operating temp. and last at that temp., heater(heating coil) is integrated with Lambda sensor.
Heater coil is controlled by ECM as PWM. the resistance of heater coil is low when coil is cold thus, current through it increases while resistance is high when coil is hot thus, current decreases. With this principle, Lambda sensor temp. is measured and Lambda sensor heater operation varies based on the data.

DTC Description

When ECM detects short to ground in the heater control circuit(S1), ECM sets DTC P0031.

DTC Detecting Condition

** S1 : upstream oxygen sensor / S2 : downstream oxygen sensor

Specification

Diagnostic Circuit Diagram

Signal Waveform & Data

The HO2S requires a minimum temperature to provide a closed loop fuel control system. So the HO2S contains a heater element to reduce its warm-up time and ensure its performance during all driving conditions. The HO2S heater is controlled ON after engine start except for Cold condition and high speed accelleration. 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.