* Two upstream sensors: These are located in the exhaust manifold, before the catalytic converters. One is on each header/bank of cylinders. They're usually fairly close to the engine, and may require getting underneath the vehicle for access.
* Two downstream sensors: These are located after the catalytic converters, in the exhaust system. Again, one per bank. They are further down the exhaust system than the upstream sensors. Accessing these also typically requires working underneath the vehicle.
Important Note: You'll need to consult a repair manual specific to your 2003 Dodge Ram 1500 5.7L. A diagram showing the exact location of the oxygen sensors will be invaluable. These manuals are available online or at auto parts stores. Incorrect sensor replacement can lead to further engine problems.
