precat O2 sensor replacement write-up?
 

2001 audi A4 1.8T FWD 143,000 miles.

I'm looking for a DIY to replace the precat O2 sensor, I've searched and searched and can't find anything. I'm getting terrible gas mileage since I threw the CEL (I just moved, took it to stealership b/c it was really close so they could do the ignition coil recall 3 months ago, and thermostat replacement because heater was working poorly and so a few weeks later it threw the CEL about the O2 sensor.they didn't log the code, of course!, but said it was bank 1 sensor 1

anyways, just threw another code after getting my own OBDII reader, it said P0411. I know that could be multiple causes like combi-valve, hoses, MAF sensor, etc...but I thought I would start with the O2 sensor (I'm replacing the coolant temperature sensor as well because that is faulty.

if there is anyone who could help that would be great I'm really sick of getting poor gas mileage and don't want to hurt the cat.

all of you are so knowledgeable and I look forward to posting more and filling out my profile, I've been a reader of this site for years but never posted.

1. Get an O2 sensor ratchet tool, ratchet, universal joint, and long ratchet extension.

2. Unplug the O2 sensor. The plug is on the drivers side behind the coolant reservoir. You need to move the reservoir. It's 3 phillips head screws and just move it towards the front of the car to get access. I can't remember what color the plug is, but you have a new sensor so it should be the same color as your new O2 sensor plug.

3.There's a wire holder on the back of the head. There's no need to cut it, just undo it.

4. Take your fancy ratchet concoction and unscrew the sensor. You might need some liquid wrench to get it out.

5. Plug in your new sensor, run the cable the same way your old one went.

6. Drink beer.

Note: If you take out the oxygen sensor first, you can twist the wires and break them. So don't do that.

Note: use high-temperature anti-seize compound on the new sensor. Some sensors come with it.

note.. Enjoy the car when you done =]