Before I go to a dyno, do I have to make sure they have a wideband 02 or do all dyno's have that.... Also, what is it?

 

Most dynos have a wideband O2 sensor for the tuning process.

A wideband O2 sensor is a very acurate O2 sensor which measures the amount of oxygen in your exhaust gas and changes the air fuel ratio accordingly to keep the proper amount of air and fuel being combusted..

 

So they will have a wideband o2 sensor that i switch with mine before tuning.... then when i am done, i put my o2 sensor back in?