Lambda sensor spanner size

[rb_stretch]

I've been trying to fit a Wunderlich Y piece this evening, but couldn't take the sensor out because the biggest spanner I had was 19mm.

Searched the forum to know what size I need to buy and found two sizes given 20mm and 22mm - so which one is right??

Thanks
RB

 

[IainMac]

I believe its a 22mm.