My wife's catalytic converter was sawed out and stolen on her 2003 TL so we had the local muffler shop welded in a universal one. The bung hole is in the middle of the catalytic converter- so should I buy an upstream or downstream O2 sensor?

Seeing multiple options on Rockauto:
https://www.rockauto.com/en/catalog/...2)+sensor,5132

Thanks!

 

The shop told me downstream but I want to be sure before I order it.

 

Downstream

 

Thanks!

I'm going to order the Denso downstream O2 sensor. Think there will be any issues with readings/measurements of the O2 sensor on a universal catalytic converter rather than an OEM-style one?

 

As long as the converter is doing it's job then it shouldn't be an issue.