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Hi, My car is saying that I need to change the lambda sensor (error code 17521) on bank 1 probe 1 and I was wondering if this was a job that was possible to DIY. I've checked the error code and if I clear the code it will return in a few days. I'm quite practical and have for example changed all the brake pads on my car. I've spoken to the garage and they say it is a long job with the removal of lots of parts!! I would be doing the job on the road by driving the car up some floor ramps and working from below. Would this be a nightmare or are there any hints and tips that make it possible. My car has done 100,000 miles now and is beginning to cost £, I'm just trying to do the work myself so I can afford to keep it.

Also should I change both pre CAT sensors and the same time??

Is the Bentley Manual any good? Maybe its worth buying one for the future, does anybody have one? if so whats the section of replacing lambda sensors of the 4.2 like?

Thanks in advance!!

Hello Mate,

After about 6 months of my car was telling me this. Two Lambda probes needed changing so were removed and check as correct by my local Audi non franchised garage, so we've finally found the problem to be two vacuum hoses which regulate oxygen pressure with in the engine. There was no noticable holes in them but they were ever so slightly collapsed. I have now done 300 miles since the change without any probs. The management light was coming on about every 20 miles while the problem ewas fully diagnosed. It only cost £90 within the M25 area so was a proper bargain for London. I was quoted £750 by Watford Audi for the replacement Lambda sensor work and they were't even faulty. My local quoted me £400 and checked before hand so got it right!

Good luck and if you've been noticing a slight drop in fuel consumption (mine dropped to 18mpg) then this could be the common problem I've been assured many S6's suffer.

Tony

It looks like a big enough job, you need to drop the subframe and remove the exhaust on that side.. It might be worth a quick look underneath to see if you actually need the subframe etc out. I bought the Elsawin CD off ebay, it is quite useful.. see the Lamdba section below.

http://homepage.ntlworld.com/ashcrawford/Lambda.pdf

Thanks for replies!!! I don't really have the ability to remove subframes without a ramp, I was wondering if that was the only way! I guess there's a lot of engine and not much room for hands.

Tony, thanks also, do you know which 2 hoses and I'll give them a check?

I would still stick it up on the wheel ramps and have a look, you might be able to drop the exhaust and do it without the subframe..

Hello,

I can't remember what they were called but I believe there is only two of them coming out of the bottom of the engine and need a few bits removing to get at them.

I'll get back to you with more when I speak to the mate who did it. He's away for the weekend.

Good luck,

Tony

mine needs replacing too, will the NGK ones be ok, as i heard unless u get originals it keeps throwing fault code??