目前，汽車上采用的進口氧傳感器(qi)有氧化鈦（TiO2）式和氧化鋯（ZrO2）式兩種。氧化鋯式氧傳感器又分為加熱型氧傳感器和非加熱型氧傳感器兩種。氧化鈦式氧傳感器本身帶有一個電加熱器。大部分汽車使用帶加熱器的氧傳感器，這種傳感器是在原來傳感器的基礎上，增加了一個陶瓷加熱元件用于加熱傳感器，可在發動機啟動后的20~30s內迅速將氧傳感器加熱至工作溫度，擴大了空燃比閉環控制的工作范圍，故又稱為加熱型氧傳感器。
進口氧傳感器有一(yi)(yi)線(xian)(xian)制(zhi)(zhi)(zhi)(zhi)(zhi)、二線(xian)(xian)制(zhi)(zhi)(zhi)(zhi)(zhi)、三線(xian)(xian)制(zhi)(zhi)(zhi)(zhi)(zhi)、四線(xian)(xian)制(zhi)(zhi)(zhi)(zhi)(zhi)4種類(lei)型，其(qi)結構如圖1所示。一(yi)(yi)線(xian)(xian)制(zhi)(zhi)(zhi)(zhi)(zhi)只有一(yi)(yi)根(gen)信(xin)號線(xian)(xian)與(yu)發(fa)動(dong)機(ji)ECU連接，傳感器(qi)的(de)另一(yi)(yi)極直接搭鐵；二線(xian)(xian)制(zhi)(zhi)(zhi)(zhi)(zhi)的(de)兩(liang)(liang)根(gen)線(xian)(xian)均(jun)與(yu)ECU相連，一(yi)(yi)根(gen)為信(xin)號線(xian)(xian)，另一(yi)(yi)根(gen)進入(ru)ECU后搭鐵；三線(xian)(xian)制(zhi)(zhi)(zhi)(zhi)(zhi)、四線(xian)(xian)制(zhi)(zhi)(zhi)(zhi)(zhi)均(jun)屬于(yu)加(jia)熱式(shi)氧傳感器(qi)，由于(yu)添加(jia)了(le)兩(liang)(liang)根(gen)加(jia)熱電(dian)(dian)阻(zu)的(de)接線(xian)(xian)，和氧傳感器(qi)信(xin)號線(xian)(xian)組合成為三線(xian)(xian)制(zhi)(zhi)(zhi)(zhi)(zhi)或四線(xian)(xian)制(zhi)(zhi)(zhi)(zhi)(zhi)。加(jia)熱電(dian)(dian)阻(zu)的(de)兩(liang)(liang)根(gen)接線(xian)(xian)，一(yi)(yi)根(gen)直接接控(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)繼(ji)電(dian)(dian)器(qi)或主繼(ji)電(dian)(dian)器(qi)，接受12V加(jia)熱電(dian)(dian)源(yuan)，一(yi)(yi)根(gen)由ECU控(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)搭鐵端，控(kong)制(zhi)(zhi)(zhi)(zhi)(zhi)加(jia)熱電(dian)(dian)阻(zu)加(jia)熱時間。
進口氧傳感器加熱器是正比(bi)例(li)系數熱敏元件，在傳感(gan)器與線(xian)束斷(duan)開的情況(kuang)下，可(ke)以通過檢測加熱器的阻值來(lai)對加熱元件進行檢測。
隨著排(pai)放(fang)法規越來越嚴格(ge)，現在(zai)越來越多的車輛都(dou)在(zai)三元(yuan)催(cui)(cui)化(hua)(hua)(hua)轉化(hua)(hua)(hua)器(qi)(qi)(qi)(qi)的前(qian)后端分別(bie)安(an)裝了氧(yang)(yang)傳感(gan)器(qi)(qi)(qi)(qi)，稱為(wei)雙氧(yang)(yang)傳感(gan)器(qi)(qi)(qi)(qi)系統(tong)，一(yi)(yi)個在(zai)三元(yuan)催(cui)(cui)化(hua)(hua)(hua)轉化(hua)(hua)(hua)器(qi)(qi)(qi)(qi)之(zhi)前(qian)，稱作為(wei)主氧(yang)(yang)傳感(gan)器(qi)(qi)(qi)(qi)或(huo)上游氧(yang)(yang)傳感(gan)器(qi)(qi)(qi)(qi)，用于(yu)混合氣(qi)反饋控制(zhi)，發動(dong)機電控單元(yuan)根(gen)據主氧(yang)(yang)傳感(gan)器(qi)(qi)(qi)(qi)的反饋信號，增加或(huo)減少噴(pen)油量，將實際空燃比(bi)控制(zhi)在(zai)理論空燃比(bi)附近(jin)；另一(yi)(yi)個位于(yu)三元(yuan)催(cui)(cui)化(hua)(hua)(hua)轉化(hua)(hua)(hua)器(qi)(qi)(qi)(qi)之(zhi)后，稱作副氧(yang)(yang)傳感(gan)器(qi)(qi)(qi)(qi)或(huo)下游氧(yang)(yang)傳感(gan)器(qi)(qi)(qi)(qi)，用于(yu)監測(ce)三元(yuan)催(cui)(cui)化(hua)(hua)(hua)轉化(hua)(hua)(hua)器(qi)(qi)(qi)(qi)的催(cui)(cui)化(hua)(hua)(hua)凈化(hua)(hua)(hua)效率(lv)。
當三元催化(hua)(hua)轉(zhuan)化(hua)(hua)器(qi)損壞時(shi)(shi)，其轉(zhuan)化(hua)(hua)效(xiao)率喪(sang)失，這時(shi)(shi)在其前后的排氣(qi)管中的氧氣(qi)量十分接近，幾(ji)乎相(xiang)當于(yu)沒有安裝三元催化(hua)(hua)轉(zhuan)化(hua)(hua)器(qi)，前、后兩個氧傳感器(qi)的信(xin)號(hao)電壓波形就趨于(yu)相(xiang)同，并且電壓波動(dong)范圍也趨于(yu)一致(zhi)，此時(shi)(shi)表(biao)明三元催化(hua)(hua)轉(zhuan)化(hua)(hua)器(qi)轉(zhuan)化(hua)(hua)能力下(xia)降。
