Hey all,
i have a 2000 a4 1.8t, i have a fault 17521 o2 sensor resistance to high, and it also says that my cat convertor is not set. which in Stupid BC canada you can not get it air cared. So question is when i get my O2 sensor before the cat fixed will my cat be fine again?

 

Not to jack your thread... But I kinda have same issue with my 2.8. But both of my o2 sensors are bad... I bought 2 new ones but I don't know where they are located.... So if anyone knows where they are and the easiest way to get to them (from top or from bottom) can u let me know.... Thanks

 

Matt- not sure if replacing the O2 will fix your cat problem, one could be causing the other, and the O2 would be much cheaper to replace first. So,give it a try, then have the code reset. If that doesn't fix your cat problem, then your cat may be bad too...

Phil- I don't have a 2.8 myself, but I'm pretty sure you actually have 4 O2 sensors, one before and after each cat. You might want to make sure you know which ones are bad. If anyone else reads this and is a little more knowledgable on the 2.8 and I'm totally off, feel free to correct me in this thread so everyone can get a good laugh at my stupidity

 

Well the code reader said side 1 and 2 1st sensor bad.... So its the first o2 sensor on each side... I just don't know t

 

Should be right before the cats then... again, never seen a 2.8, so unless Audi has a completely different design (never seen that happen yet), they should be right there between the manifold and cat...

 

ok awesome thanks.. im not gonna replace them until the CEL comes back on and i can read the codes to make sure they arent old codes... thanks again though... hope matt gets his issue fixed though