Where are the oxygen sensor on a 2003 Chevy S-10?

The location of the oxygen sensor(s) on a 2003 Chevy S-10 depends on the engine. There's usually one upstream (before the catalytic converter) and one downstream (after the catalytic converter).

To find them:

1. Consult your owner's manual: This is the best place to start. The manual will have diagrams showing the location of all sensors.

2. Check online repair manuals: Sites like Chilton or Haynes offer repair manuals specific to your year and engine. These usually include detailed diagrams and descriptions of sensor locations. Make sure you select the correct engine size for your S-10 (e.g., 2.2L, 4.3L).

3. Look under the vehicle: With the engine cool, look at the exhaust manifold and the exhaust pipe. The upstream sensor is usually screwed into the exhaust manifold close to the engine. The downstream sensor is on the exhaust pipe after the catalytic converter. They look like threaded metal cylinders with a wire harness attached.

Caution: The exhaust system gets very hot. Allow the engine to cool completely before attempting to locate or work on any parts of the exhaust system, including the oxygen sensors. Wear appropriate safety gear (gloves) as well.