2001 S8 Lambda Sensor info please?

[HPsauce]

My post-cat lambda was totally stuck in when they replaced my nearside cat the other day.
They removed it eventually on the bench (to send the old cat back) but the thread was too damaged to reuse.
Shame as it was otherwise still perfectly ok.

New one cost £67.99 plus VAT, I think from TPS.
That wouldn't be a cheap one, my garage only use OEM (or main manufacturer equivalent) so presumably a Bosch one.

[brasiliangringo]

They are all pretty much the same, i have cut and crimped heads from different number BOSCH sensors provided they have the same number of wires ie 5 wires are wideband narrow 3. Never solder as this prevents atmospheric air from getting down into the sensor head needed by the sensor to calc the diff between normal o2 in atmosphere and that in exhaust gases. I have tried it and you get a code with solder (!) which seals off the fresh air supply from traveling down between the insulation and wire - hard as it is to believe from looking at the wires!

[brasiliangringo]

Get the Bosch number and search it out like that - diff countries also have different numbers to complicate it but there are some fairly cheap Bosch vendors if you sniff out the correct Bosch PN - whether it works for sourcing one for the S8 i cant say but worth a go..

[brasiliangringo]

Originally Posted by Cornershop

folks!

Can anyone recommend an alternative source for the front lambda sensors as both my pre-cat are flagging in vcds, according to my indie.

Audi want 160+vat each (seems everything I needto change is 160 + vat )

I believe Bosch 0258006159 are equivalent - anyone tried these at circa half the price?

Cheers

Yes with different cars no problem, the sensor heads are all generally the same with exception of narrow and wide band sensors - the latter can measure fuel trims at WOT.

[HPsauce]

My post-cat lambda was a Bosch 0258010073. About £70 on Amazon.
I would expect the pre-cat to be similar/identical.

[ainarssems]

I have in the past (not on 8) also use different Bosch lambda sensor from different car by just changing the plug from original. I did solder it and it still worked without any issues but it was not easy to solder as the wires were stainless steel instead of copper. Most of them are the same with difference being cable length and plug but there are some odd ones with different size.

As far as narrowband/wideband go most of production cars are narrowband with exception of some exotic cars and fuel stratified engines which run lean. Difference between 3(2) wire vs 5(4) wire is that extra 2 wires are used for heating element to bring it up to temp sooner and pretty much all these days are heated versions except for some older cars. Most narrowband come with 4 wires these days, wideband will normally have 5 or 6 wires.

[brasiliangringo]

Plenty of cars have wide band - the Mk1 TT / S3 BAM does and that was made in 2000/2001 not new or exotic really. (All the 2.0 TFSIs have wide band, common as muck)

Soldering is considered a no no for wiring up o2 sensors and that's the manufacturers advice given how they function, not mine. You may ofc get lucky as you did if there is a slight gap with solder to allow air travel.

[Goran]

Sorry to hear they are both stuck. I guess its best not to second-guess the mechanic, I wonder if some anti-seize product might dislodge them.
My mechanic removed both of mine from above, no exhaust dismantling needed, at 80k, but maybe I was lucky that they weren't stuck.
His trick is to use a crow's foot wrench and long 1/4" or 3/8" extension and remove only the SAI combi valves (polished steel mushroom shaped things on back of the engine block).
It was really quick doing it this way.

[brasiliangringo]

He did the pre cats on an S8 without removing the pipes ?

[brasiliangringo]

Impressive work on his part if it was. I never gave it any thought but obv is possible if they are not too stuck - worth trying 1st then, but i think you were lucky as they often need a hex deep o2 socket and impact wrench to shift.