Note. For circuit reference, see WIRING DIAGRAMS article.
Circuit Description
The Heated Oxygen (HO2S) No. 2 heater increases the amount of time sensor spends in closed-loop fuel control operation or catalyst monitoring operation. Oxygen sensor heater greatly reduces amount of time required for HO2S 2 to become active. Oxygen sensor heater is required by post-catalyst HO2S 2 in order to maintain high operating temperatures. Heater helps provide accurate oxygen content readings of engine exhaust by HO2S.