Hey all. I have a 2000 A4 2.8L. CEL has been on for last bit. Had the codes read and the oxygen sensors reset. First time indicated Bank 1 Sensor 1. CEL came back on a month later and it read Bank 2 Sensor 2. Audi recommended i get the catalytic converters replaced. I believe this is a DIY job, no?

My questions are:
1. There are 4 oxygen sensors, 2 before, 2 after? Should I replace all 4?
2. What code reader do you recommend I buy for myself and where should I get it?
3. What tools do I need to do this? Oxygen sensor wrench? Extensor?
4. Where are they located in reference to the car itself? Do I have to get the car lifted or put on blocks?
5. How do I reset the CEL afterwards?
6. A friend who works at NAPA said he was surprised the CATS would need to be replaced...he said they have to physically break and it would be more prudent to replace the 02 sensors first.
7. I've been driving with the lights on for the last month - how bad is this?

Thanks
Jonathon

 

Wilkommen to the forums!

1. Typically if one is going the others are not far behind. If you have the means replace all 4

2. Vag-Com. go to Ross-Tech.com for the specifics. You don't need the really expensive set, the basic setup is listed for $250 (IIRC). You can find them as cheap as $220 (ish) at various online retailers. You can sometimes find them previously enjoyed on the classifieds (this and other forums) or ebay for under $200. You can go with an unlicensed cable from ebay (~$20) and use the free version of the software (VCDS-Lite) but you are taking your chances on functionality. These solutions require you to have a computer (preferably a lappy with micro$oft OS). Alternatively, any OBDII scanner will read most of the codes but may not be able to reset certain things and will not allow you to manipulate the modules.

3. Pretty much any good crows foot O2 wrench (22mm i think) should do the trick. You may need a wobble and a ratchet with a couple of extensions is usually sufficient for the pre-cat sensors (the most difficult to get at).

4. Pre-cat sensors are in pretty much right under the front of the firewall on both sides of the engine. These are the most difficult to reach but can be accessed from under the hood, straight down the firewall. You will have to move some things out of the way to get at them (coolant tank on the one side and intake components on the other). Put a couple of extensions on your wrench and maybe a wobble. The post-cat sensors are pretty straightforward, underneath just after the cats. You will want the car on jackstands (or equivalent) for these.

5. The CEL should go off by itself if the sensors were the problem. Might take 100 miles of driving or so.

6. Yep

7. If the O2 sensors are indeed the problem it is not horrible. However, you are running a risk by continuing to drive the car without replacing the sensors.

good luck

 

What is the risk of running the vehicle with the o2 sensors bad? Because my vehicle is throwing 3 bad o2 sensors and i didnt really wanna get those fixed right away plus the cost of them was like 260 dollars not including how difficult its gonna be to replace them.

 

Bad o2's can lead to bad cats


And **** my cel's been on most of the 6 yrs I've owned the car for one reason or another