Circuit/System Description

WARNING: This page is about a different car, the 2007 Pontiac G5 Pursuit, 2007 Pontiac G5, and 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by an ignition voltage circuit through a fuse. With the engine running, ground is provided to the heater by the HO2S heater low control circuit, through a low side driver within the engine control module (ECM). The ECM uses pulse width modulation (PWM) to control the HO2S heater operation to maintain a specific HO2S operating temperature range.

P0030 or P0036

The ECM monitors the voltage on the HO2S heater low control circuit for heater fault diagnosis. If the ECM detects that the HO2S heater low control circuit voltage is not within a specified range, DTC P0030 sets for HO2S 1, or DTC P0036 sets for HO2S 2.

P0053 or P0054

The ECM determines the temperature by measuring the current flow through the heater and calculating the resistance. Based on the resistance, the ECM can predict the sensor temperature. The HO2S uses pulse width modulation (PWM) to control the heater operation. The ECM calculates the heater resistance on a cold start. This diagnostic will only run once per ignition cycle. If the ECM detects that the heater calculated resistance is not within the expected range, DTC P0053 sets for HO2S 1, or DTC P0054 sets for HO2S 2.

P0135 or P0141

If the ECM detects that the heater current is not within the expected range, DTC P0135 sets for HO2S 1, or DTC P0141 sets for HO2S 2.