SRT-4 L4-2.4L Turbo VIN S (2004)
Downstream Heated Oxygen Sensor 1/2
Heated Oxygen Sensor Systems
The downstream heated oxygen sensor threads into the system depending on emission package. Federal package the O2s is mounted after the catalytic
converter, LEV package the O2s is mounted mid catalytic converter, ULEV package is mounted between the catalytic converter.
A separate upstream and downstream grounds are used on the NGC vehicles (4 Cyl.).
As vehicles accumulate mileage, the catalytic converter deteriorates. The deterioration results in a less efficient catalyst. To monitor catalytic converter
deterioration, the fuel injection system uses two heated oxygen sensors. One sensor upstream of the catalytic converter, one downstream of the converter.
The PCM compares the reading from the sensors to calculate the catalytic converter oxygen storage capacity and converter efficiency. Also, the PCM
uses the upstream heated oxygen sensor input when adjusting injector pulse width.
When the catalytic converter efficiency drops below emission standards, the PCM stores a diagnostic trouble code and illuminates the malfunction
indicator lamp (MIL).
The O2 sensors produce a constant 2.5 volts on NGC vehicles, depending upon the oxygen content of the exhaust gas. When a large amount of oxygen is
