To find it accurately:
1. Consult your vehicle's repair manual: This is the most reliable way to find the precise location with diagrams. A Haynes or Chilton manual, or a digital version, will be very helpful.
2. Use a online repair database: Sites like AllDataDIY or Mitchell 1 (subscription required) will have detailed diagrams and specifications for your specific year, make, model, and engine.
3. Search online forums: Search forums specific to the 2005 Chevy Avalanche (mentioning the engine size) – someone may have already posted a picture or description of its location.
Generally, it's a small sensor with a single wire, often near the oil filter or other engine components. Be careful when searching, as the engine is hot when running.