I recently switched from a single wire to a three wire heated oxygen sensor since I got headers. I've got the power wire hooked up to the wire going to the fuel pump fuse as I understand it is only supposed to be hot when the car is on. I'm not so sure this is true anymore since I've had this thing in my battery has been going dead on me. I've had the battery and alternator tested so I know it is no fault of theirs. What did I mess up???

Just to prove that it wasn't anything else and was just coincidence I removed all the fuses in the car one by one and tested the amp draw from the battery by having a multimeter inline between the disconnected positive wire and the battery. It didn't stop drawing until I removed the fuse for the fuel pump, and to be doubly sure it was the O2 sensor I disconnected it and reconnected the fuse and it was no longer drawing.

 

Put a test light on the wire / fuse under the hood that you think is the fuel pump. The power should be KEYED as-in when the key is shut off it will not have power.

 

If you're feeling frisky and want to do this right, here is a wiring method we came up with years ago (credits Vader for the diagram) that will run the sensor heating element based on the car being in open/closed loop.

 

I'm not sure if the diagram will work since I have the EBL and the pinout is slightly different and the EVAP is no longer used.

 

lol I didn't even pay attention to the vehicle you were referring to. The point of that method was to have it to where the sensor was only heating in open-loop mode. I didn't use that pin, I used the wire from the AIR divert solenoid. When the vehicle is in closed-loop mode, air is being sent to the catalytic converter. So I keyed off of that wire.

 

check this out
https://www.thirdgen.org/forums/elec...ghlight=heated

let me know what you think of my work