gregukCommunity MemberJanuary 19, 2021 at 3:03 pm
Hi I have a p0420 code with a check engine light in my toyota corolla. Tried to reset the codes two times but it keeps coming back. what could be the problem?MSelleenAdministratorJanuary 19, 2021 at 5:28 pmold garage mechanicCommunity MemberNovember 10, 2021 at 10:36 pm
On all cars made after 1995, there are 2 types of oxygen sensors, code PO420 has to do with the exhaust. what is referred to as an “upstream” and “downstream” sensor. The upstream sensor does most of the work in determining the air/fuel ratio of the vehicle, while the downstream sensor is located after your catalytic converter, and it’s there to monitor exactly how your converter is performing
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