Unknown cat sensor

[Seb_]

Hi everybody
I was wondering what was the bottom sensor on the japanese March 1s cat "SEC226" on the diagram:

On the bottom left side on the attached picture:

Any information/reference would be helpful..

Thank you

 

[infinity]

Second lambda??

 

[Seb_]

I think so, because Marches manifold lambda got only one wire. I don't have anymore informations on this one tho.