To find them specifically, you need to know your engine size (e.g., 2.2L, 4.3L). Then:
* Consult your vehicle's repair manual: This is the most reliable source. It will show diagrams and precise locations for your specific engine.
* Use an online repair manual: Sites like Chilton or Haynes offer online access to repair manuals. Search for your specific year, make, model, and engine.
* Look under the vehicle: The sensors are usually threaded into the exhaust pipe or manifold. They are typically wire-connected and have a small cylindrical or flat-pack shape. Be careful when looking underneath, as the exhaust system is hot.
General Locations (but not guaranteed for your specific truck): You'll likely find at least one O2 sensor before and one after the catalytic converter, if your S-10 has one. They're usually located close to the engine manifold or in the exhaust pipes themselves, but the exact spot varies depending on engine configuration and exhaust routing.
Safety First: Remember to let the engine and exhaust system cool completely before attempting to locate the sensors. Exhaust components can be extremely hot and cause serious burns.