Where would a 2000 Chevy Blazer oxygen sensor 3 be located?

The location of the Oxygen Sensor 3 (O2 sensor 3) on a 2000 Chevy Blazer depends heavily on the engine configuration (e.g., 4.3L V6, 5.7L V8, etc.) and whether it has a catalytic converter before or after the sensor. There's no single universal location.

To find it, you'll need to:

1. Consult your vehicle's repair manual: This is the most reliable source. The manual will have diagrams showing the exact location of all sensors, including the O2 sensors.

2. Use a repair database: Online resources like AllDataDIY or Mitchell 1 (subscription required) have detailed diagrams and information specific to your vehicle's year, make, model, and engine.

3. Look near the catalytic converter(s): O2 sensors typically monitor the exhaust after the catalytic converter(s). Sensor 3 is usually downstream of the converter, but again, this depends on the configuration. Look along the exhaust piping near or after the catalytic converter(s). They're usually threaded into the exhaust pipe.

4. Check online forums: Search online forums specific to Chevy Blazers (like BlazerForum.com) mentioning your year and engine. Someone may have posted about replacing their O2 sensor 3, including a picture of its location.

Important Note: Always be careful when working around the exhaust system. It will be hot even after the engine has been off for a while. Wear appropriate safety gear, including gloves.