Ngokuvamile, ingqondo yobunjiniyela yesistimu yokulawula impendulo kaphethiloli inquma ukuthi inzwa ye-oxygen iseduze negumbi elivuthayo, futhi ukuphakama kokunemba kokulawula uphethiloli kuba, okunqunywa ikakhulukazi izici zokugeleza komoya wokukhipha umoya, njengejubane legesi, ubude besiteshi (igesi isala ngemuva ngokushesha) kanye nesikhathi sokuphendula senzwa, njll. Abakhiqizi abaningi bafaka inzwa ye-oxygen ngaphansi kwe-multifold exhaust ngayinye ye-cylinder ngayinye, ukuze ikwazi ukunquma ukuthi iyiphi i-cylinder enenkinga, okuyinto iqeda ukuthi kungenzeka iphutha lokuxilongwa, futhi ezimweni eziningi kunciphisa isikhathi sokuxilongwa ngokuqeda okungenani ingxenye yamasilinda angaba yinkinga. Isiguquli esivamile se-catalytic esinenzwa yomoya-mpilo ekabili kanye nesistimu yokulawula impendulo kaphethiloli evame ukulawula isistimu yokusabalalisa uphethiloli ingaqinisekisa ukuguqulwa okuphephe kakhulu kwezingxenye zokukhipha umoya eziyingozi zibe i-carbon oxide engenangozi nomhwamuko wamanzi. Kodwa-ke, isiguquli se-catalytic sizolimala ngenxa yokushisa ngokweqile (ngenxa yokuntula okuncane, njll.), okuzoholela ekuncishisweni kwendawo ye-catalyst kanye nokucwiliswa kwensimbi ye-orifice, kokubili okuzolimaza unomphela isiguquli se-catalytic.

Lapho i-catalyst ihluleka, singakwazi ukwazi ukuthi ochwepheshe babaluleke kakhulu ekulungiseni imvelo kanye nesistimu yokukhipha umoya.

Ukubonakala kwesistimu yokuxilongwa kwe-OBD-II kwenza uhlelo lokuqapha ebhodini kanye nesistimu yokuqapha ye-OBD-II yemvelo kanye ne-catalyst yokutholwa okunembile kusho ngokwezimpawu ze-oxidation zama-catalysts amahle noma amabi. Ekusebenzeni okuzinzile, ukushintshashintsha kwesignali kwenzwa ye-oxygen enhle (eshisayo) ngemuva kwe-catalyst kufanele ibe ngaphansi kakhulu kunanoma iyiphi inzwa ye-oxygen phambi kwe-catalyst, ngoba i-catalyst evamile yokusebenza isebenzisa umthamo we-oxidation lapho iguqula ama-hydrocarbons ne-carbon monoxide, okuyinto yehlisa ukuguquguquka kwesignali kwenzwa yangemuva komoya-mpilo.