Generally, you'll find them:
* Upstream (before the catalytic converter): One or two sensors are located in the exhaust manifold or close to it, before the catalytic converter(s). These are the most crucial for engine control.
* Downstream (after the catalytic converter): One or two sensors are located after the catalytic converter(s). These monitor the catalytic converter's efficiency.
To find the exact locations for *your* specific Silverado:
1. Consult your owner's manual: This is the best source for precise sensor locations.
2. Use a repair manual: A Haynes or Chilton repair manual specific to your year, make, model, and engine will have diagrams showing oxygen sensor locations.
3. Use an online parts catalog: Websites like AutoZone, Advance Auto Parts, or Napa Auto Parts allow you to select your vehicle and see diagrams showing parts including oxygen sensors. Look for diagrams of the exhaust system.
Caution: Oxygen sensors are usually threaded into the exhaust pipe and can be difficult to access. Use caution and the right tools when attempting to locate or replace them. Exhaust systems get very hot, so let the engine cool completely before working on them.
