How many oxygen sensors are on a jeep 4.0 engine?

Answer 1

Most 4.0L engines with federal emissions have two oxygen sensors located on the exhaust pipe before the muffler. One sensor is mounted before the catalyst (upstream) and one is mounted after the catalyst (downstream). Most 4.0L engines with California emissions have four oxygen sensors. These are mounted in the exhaust manifold area. Two are upstream and two are downstream. There is an emissions label under the hood of the vehicle that identifies the emissions type.