Circuit description

The engine control computer uses two sensors installed on the front and rear of the three-way catalytic converter to monitor the clean-up condition of the catalyst. At the same time, the air/fuel ratio sensor transmits an air/fuel ratio signal at the front of the catalyst to the engine control computer. At the same time, the oxygen sensor transmits an oxygen level signal after catalyst to the engine control computer. The engine control computer uses output voltage of the air/fuel ratio sensor and the oxygen sensor to calculate oxygen storage capacity (hereafter called OSC) and detects deteriorated condition of the catalyst.