Where is oxygen sensor 1999 Chevy Blazer?

The location of the oxygen sensor on a 1999 Chevy Blazer depends on whether it's a 4.3L V6 or a 5.7L V8 engine, and even then there are multiple oxygen sensors. There's usually one upstream (before the catalytic converter) and one or more downstream (after the catalytic converter).

To find it, you'll need to:

1. Consult your vehicle's repair manual: This is the most accurate way to determine the exact location of your oxygen sensors. The manual will have diagrams showing sensor placement.

2. Use an online parts diagram: Many auto parts websites (like AutoZone, Advance Auto Parts, etc.) allow you to select your vehicle's year, make, model, and engine size. Then you can usually view diagrams showing the location of components, including oxygen sensors. Search for "1999 Chevy Blazer oxygen sensor location" on these sites.

3. Look under the vehicle: The upstream oxygen sensor(s) is usually located in the exhaust manifold or close to it. Downstream sensors are typically located further down the exhaust system, after the catalytic converter(s). Be careful when inspecting underneath your vehicle, use jack stands and follow safety procedures.

Without knowing the engine size, it's impossible to give you a precise location. The repair manual or online parts diagram is crucial for accurate identification.