Circuit Description
ECM monitors oxygen concentration in the exhaust gas which has passed the three way catalytic converter by HO2S-2.
When the catalyst is functioning properly, the variation cycle of HO2S-2 output voltage (oxygen concentration) is slower than that of HO2S-1 output voltage because of the amount of oxygen in the exhaust gas which has been stored in warm up three way catalytic converter and three way catalytic converter.