why does my 94 s10 tahoe LT A2 have a 3 wire 02 sensor? other than starting to work faster... my retired 94 tahoe lt had a 2 wire. whent to swap it because my retired one had a brand new one.. and awh snap 3 wires instead of 2. is there another difference in the motor or cpu. this is the only difference that i know of on the two blazer both w vin.

 

Do you know if the 94 tahoe was equipped with California emissions and the other wasn't?

 

that was my only other thought.. how would you tell that? but i know it stayed in NJ it's whole life till i brought it to PA

 

I'm honestly not really sure how to tell on the EFI motors. There might not even be a difference on EFI motors anyways

A quick search on Auto Zone's website (for a 1994 S10 Blazer 4x4 4.3L CPI) shows that they could be a 4 wire or a 3 wire O2 sensor.