× Auto Repair Pros Member Benefits TechHelp Knowledge Base Forums Resources My iATN Marketplace Chat Pricing About Us Join Industry Sponsors Video Members Only Repair Shops Auto Pro Careers Auto Pro Reviews
Join Now
International Automotive Technicians Network
Re: California Emissions Subaru
Posted to Emissions Forum on 9/8/2018 2 Replies

The 3rd/last O2 sensor in the exhaust is for rear fuel trims. You should see a pid for such in the ECM. If I recall, it's for monitoring cats and allows the ECM to richen the fuel trims to keep the cats lit. I've only seen it a handful of times on Subarus and ... Login to read more.

2 Replies Received (View Replies)