2 years ago
Last edited at 7:21AM on 12/1/2011
V 6 and V 8 engines often have one on each exhaust manifold, as well as one/s after the catalytic converter/s. A scanner should show the O2 sensors. Bank 1 bank 2 etc. Upstream, meaning on or near the manifold/s, downstream meaning on the exhaust system, under the car, after the converter. The ones that are upstream tell the computer how to adjust the mixture rich/lean. The downstream ones monitor the performance of the catalytic converter/s. Primarily for emissions inspection. If the car burns oil, or has had problems with the head gasket, the converter can be ruined. Find a discount muffler shop and get prices for generic converters.