I'm trying to fix up this 99 outback I was given and I have ran across a dilemma. The exhaust looked solid to begin with but, I've found a few issues. Firstly I'm missing 2 out of the three o2 sensors,the rear o2 sensor is snapped off flush and is rust welded in, and I have flang issues. Overall the exhaust is structurly solid and I would like to use as much of it as I can, but I don't want to have a check engine lite and I don't see any way of repairing the rear 02 sensor without replacing that section of the exhaust.

 

My question is, can the rear o2 sensor be bypassed without causing a check engine light? I'm not concerned about passing emmisions, I just don't want to have a check engine light on.

look up o2 sensor eliminator. They may still exist, but they may not. They were a resistor that you wired in.

 

I recently welded an o2 sensor bung back in with a stick welder, so if its still there enough, you can fix it.

I was thinking about welding a new o2 bung in myself but, I thought that there might be an easier fix. I thought I remembered the eliminator fix and like you said it was a resistor I beleive. I'll try a search and see if I can find it.

I found a few different eliminator kits, but I'm not sure which one to use. In theory if I got the right resistor I should be able to solder it in and call it good.

I can't find much info on where to get the eliminator kits and when I did a google search it seems they make them for bikes more than cars. I found a post talking about this and I think it says that the rear o2 needs to see 450mv to be in optimal range. So if I were to buy a 450mv resitor thereticaly I could solder that into the circuit and eliminate the rear o2 sensor?

Okay obviously that wasn't correct since I forgot resistors are measured in ohms and not milivolts. Damn this is confusing as heck.