Fuel Control Heated Oxygen Sensors

Primary System Based Diagnostics
There are primary system based diagnostics which evaluate system operation and their effect on vehicle emissions. The primary system based diagnostics are listed below with a brief description of the diagnostic functionality.

The Catalyst Monitor Heated Oxygen HO2S 2 is diagnosed for the following functions:
- Heater Performance (time to activity on cold start)
- Signal fixed low during steady state conditions or power enrichment (hard acceleration when a rich mixture should be indicated).
- Signal fixed high during steady state conditions or decel fuel mode (deceleration when a lean mixture should be indicated).
- Inactive Sensor (output steady at approx. 438 mV)

Fuel Control Heated Oxygen Sensors
The main function of the fuel control heated oxygen sensors is to provide the control module with exhaust stream information to allow proper fueling and maintain emissions within mandated levels. After it reaches operating temperature, the sensor will generate a voltage, inversely proportional to the amount of oxygen present in the exhaust gases. The control module uses the signal voltage from the fuel control heated oxygen sensors in "closed loop to adjust fuel injector pulse width. While in closed loop, the Control Module can adjust fuel delivery to maintain an air/fuel ratio which allows the best combination of emission control and driveablity.
If the oxygen sensor pigtail wiring, connector or terminal are damaged, the entire oxygen sensor assembly must be replaced. Do Not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have a clean air reference provided to it. This clean air reference is obtained by way of the oxygen sensor wire(s). Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degrade oxygen sensor performance.