Circuit Description

In order to control emissions. a catalytic converter is used to convert harmful emissions into harmless water vapor and carbon dioxide.

The powertrain control module (PCM)/engine control module (ECM) has ability to monitor this process by using a Heated Oxygen Sensor (HO2S2). The HO2S2, located in exhaust stream past catalytic converter, produces an output signal which indicates storage capacity of catalyst: this in turn indicates catalyst s ability to convert exhaust emissions effectively. If catalyst is functioning properly. HO2S2 signal will be far less active than signal produced by Oxygen Sensor (O2S1).

If HO2S2 pigtail wiring, connector, or terminal is damaged, entire HO2S2 assembly must be replaced. Do not attempt to repair wiring, connector, or terminals. In order for sensor to function properly, it must have a clean air reference provided to it. This clean air reference is obtained by way of HO2S2 wire(s). Any attempt to repair wires, connector, or terminals could result in obstruction of air reference and degrade HO2S2 performance.