Generally, you'll find them:
* Before the catalytic converter(s): These are the upstream O2 sensors. They are usually located in the exhaust manifold or very close to it. There will be one for each exhaust bank (one for each side of the engine's "V").
* After the catalytic converter(s): These are the downstream O2 sensors. They are located in the exhaust pipe after the catalytic converter(s). Again, one per bank.
To find the exact location on *your* specific Silverado:
1. Consult your owner's manual: This is the best place to start. The diagrams might show the sensor locations.
2. Look under the vehicle: With the engine cool, get under your truck and visually inspect the exhaust system. The O2 sensors are usually threaded into the exhaust pipe and have a wire harness connected to them. They typically look like a small cylindrical device with a single wire coming out.
3. Use a repair manual (like a Chilton's or Haynes): These manuals usually have detailed diagrams showing the location of all components, including the O2 sensors, for your specific engine.
4. Use online resources: Websites like RepairPal or others dedicated to vehicle repair might have diagrams or information specific to your year and model.
Caution: Exhaust systems get very hot. Always let your engine cool completely before working under your vehicle.
