Just got my aem ems with build in UEGO controller and it comes with and 02 sensor atleast i think its an 02 sensor? Am i suppose to have 3 02 sensors now or can this thing screw in where my old one use to screw in? If it does replace one of the old sensors where do i put the old wiring because the new one comes with its own wiring to the sensor? I also noticed that the wiring for the new 02 sensor has a big plug on each end so how do you route that thing threw the firewall?

 

Remove the front O2 sensor and replace it with the new one. The plug for the old one connects under the valve cover piece that covers the coil packs. You won't ever need the old one unless you plug the stock computer back in.

As for routing it through the firewall, does it disconnect from the AEM EMS box where you could rout that thru the firewall because routing that big plug thru will take a lot of cutting? You could also disassemble the plug and take all of the wires out and rout it that way then put the plug back together.

 

There's a great hole to run the wide band cable through the firewall from, but if you have the plastic connector attached it will be a bit tough or maybe even impossible. Here's a shot of the hole in the firewall:


This will be found on the passenger side of the Evo and it will come out directly behind the glovebox.

You should remove the wires from the plastic connector so that you can run them through the hole in the firewall.

Make sure to avoid any hot parts or moving suspension parts when running the cable down in the engine bay.

Mark

 

also make sure NOT to cut any of the wires going to the sensor, that will throw the resistance of the wires off