NOX (oxygen) Sensor!!

Redders

Member
Has anyone had a problem with the above sensor, my 1.6 FSI went to an independant garage to have this looked at as the engine management light was on.

They tested the sensor and said it was fine and that it was the "heater activation" sensor that was causing the trouble. They replaced the heater sensor and the car was fine for a day but the light has come on again this morning!!!
 

spike

Well-Known Member
Hi Redders
The club tries and give at least one reply to all posts but this must have everyone stumped. I run a diesel so don't have any first hand experience of the FSI but a guy at work runs an 02 model and he regularly sees emissions related fault lamps which usually go away once reset. The garage can never trace the source of the problem so as long as the car runs ok they are reluctant to change bits on a trial and error basis.

Do anyother club members have similar problems ?

Cheers Spike
 

Skipton01

Well-Known Member
I have to agree with Spike on this one (not that I normally want to disagree mind you).

I too have only ever run diesel A2s. If you don't want the expense of a main dealer, try to find someone in your area that can do a VAG-COM scan and give you the results. If they clear the faults and then they re-occur, get them to re-scan and see if the fault is the same as before.

You can then go to the dealers armed with info to stop them from screwing too much money from you.

If the car is running well, then I wouldn't worry about the occasional light. If the car starts beeping at you however, it's then time to get something done.

Cheers,
Mike
 

Redders

Member
Thanks for you efforts to help. So far it has scaned by the AA, Audi and an indendant garage which all turned up the same fault. They have all tried to reset the light but it just comes straight back on again!!

It is going back to the indepandant garage tomorrow that thought they had fixed it so they can have another look.

I feel a bill for a oxygen sensor at the very least is in the pipeline!!!

I will post the result when they hopefully sort it out tomorrow.
 
Hello Redders,

The Engine Management System warning light came on on my 1.6 FSI this morning. The chap from Smith Knight Fay came out and ran the diagnostics thingy over it. He pronounced the same fault as you've got. Unfortunately he couldn't fix it straight away, so it's going in to the dealer.

I'll let you know what happens next.
 

Redders

Member
The car has been in the garage for two days now!! They say that the oxygen sensor fault has cleared but this was masking another fault and they think there is an air leak in the system somewhere.

I am waiting for a call at the moment on how they think the problem can be resolved!!
 

Redders

Member
Received the call today, they are charging me 5 hours (£300) labour which they think is a good deal as they recon that is half the time they have spent on it!!!!

They think it is the EGR valve which is another £300 fitted. Although they can't guarantee this is the problem! I have everything crossed at the moment, I am starting to run out of money!!!!
 

Darren C

Admin Team
Redders,

Sorry to hear of your troubles mate.

I suppose you have to say fair play to the stealers if they are in fact letting you off with some of the labour costs, however, £600 all in certainly justifies the 'stealer' name tag, (assuming you are correct in your assumptions).

Hope you manage to get it all sorted a.s.a.p. and at no further expense to yourself!!:mad:

Good Luck!!

Darren
 

gilesf

Member
NOX (oxygen) sensor

Hi,

Well this is an inetresting post, because I'm having a real problem with mine at the moment, here it all goes in roughly the right order of events (might not be exact as it's been a long time and I'm going on what Audi have told me):

1. Car purchased March 2003
2. Late 2005 engine management light comes on. Audi Roadside Assitance comes out and identifies a faulty NOX sensor. According to the RA they said sometimes it comes on in the rain. So turns the warning off and says give it a few weeks and see if it comes on again.
3. Jan-Feb 2006 engine management light come on again. RA called out, NOX sensor identified as faulty. Got it booked into the Audi dealer before warranty expires.
4. March 2006 goes into dealer, faulty NOX sensor replaced. (1st courtesy car).
5. April 2006 engine management light comes on again. Car's booked in. Apparently there are 3 NOX sensors?? and a different one is replaced. (2nd courtesy car)
6. May 2006. engine management light comes on again. Car booked in. Apparently the NOX sensor control unit is faulty?? It's replaced. (3rd Courtesy car)
7. June 2006. Engine management light comes on again!!! Car booked in. Apparently it's NOT the NOX sensor this time it's the ECU. been told I can have a new one fitted at £633 +VAT (4th courtesy car)

So without going into details of whose right or wrong as this is currently trying to be resolved between myself, the dealer and Audi UK. However, I'm EXTREMELY annoyed about this because i find it hard to believe that all those NOX parts have been replaced and now I need a new ECU. Maybe it was the ECU all along?? Other frustrations along the way include:

* Being told I'm not a loyal customer (having spent £15k on a brand new car) because I didn't get Audi to service it. even though the sales person said it wasn't complusory as long as I bought genuine Audi parts for the garage to fit.
* Third time it was booked in they broke some trim off, didn't tell me. Questioned whether it was me that did it.
* Been really patient and polite whilst the whole saga's been going on.
* They said four months was a long time between me first reporting it and the problem to re-occur. When that was only because I had to wait between 2-3 weeks for a courtesy car each time. (The engine management light always came back on within a week of me getting the car back).

So all in all a very frustrating situation. If anyone has had similar problems or technical knowledge on ECU's, NOX sensors etc.. I'd love to hear from you.

Thanks for taking the time to read this post and hope no one experiences similar problems.

Ta!!

(and just for your amusement, I had a rusty front panel under the bonet, when under warranty. Took it in and was told that I should be cleaning the engine bay (on an A2 with a semi fixed bonnet!!!!!!) and that it's normal for people to clean their car's engine bay every few weeks :) Luckily that got replaced)
 

Skipton01

Well-Known Member
Hello Giles,

Sorry to hear of your troubles - not what any of us want to hear or go through.

Have you got Audi UK involved in the case yet? If not, get onto them asap - they were (eventually) very helpful to me recently. As the root of your problems occurred within the warranty period, I would argue the case that the problems were not fixed fully and that although you are strictly speaking, outside your warranty period, Audi do have an obligation to correct a fault which occured within the period.

To have NOX sensors replaced in a seemingly arbitrary manner is like pinning the tail on the donkey - they might get the problem, they might not!

I am not sure of the number of NOX sensors - I'll check tonight when I get in.

First though, get onto Audi UK.

Cheers,

Mike
 

gilesf

Member
Thanks for the reply Mike. Yep, Audi UK are involved along with the dealer. Audi UK are currently saying they'll match the dealer's proposal. Basically leaving each of us (myself, dealer, Audi UK) paying a third each.

If you could look into the NOX sensors that would be great.

Thanks!!
 

Redders

Member
The garage that my car is in with initially said there were two NOX sensors but after looking on their computer confirmed that there is just the one.

They did try a new one but this didn't fix my problems so they removed it and put the old one back!!
 

Skipton01

Well-Known Member
Giles, can you send me your engine and transmission codes so that I can look at the schematics for your car please.

These are two 3-letter codes, printed on the data sticker on the insode cover of your service booklet.

Cheers,

mike
 

gilesf

Member
Hi Mike,

Unfortunately the service booklet along with my car is with the dealer. Is there anywhere else I might be able to find this information?

Really appreciate your assistance with this, so thanks again.

Giles
 

Skipton01

Well-Known Member
Right, after a sudden rush of blood to the head (see my PM Giles - you of course have the FSI, there aren't any NOX senders on 1.4 petrol cars, doh!), I've got to the bottom of the NOX issue - I think!

I've attached 3 photos, showing firstly the wiring between the sender, the control unit and the ECU and then 2 diagrams showing the locations of the parts involved (to orientate yourself, the NOX sender diagram shows the underside of the car and the exhaust pipe, the control unit diagram is showing the passenger footwell compartment).

As you will see, there is ONLY 1 NOX SENDER.

Also, the wiring all leads back to the ECU, so it could well have been a faulty ECU to start with. I know exactly what the dealers have done - they started by replacing the least expensive part (the sender), then when this didn't work, they moved on to a more expensive part, and now finally, they're going for the daddy, in cost terms - the ECU.

They did this with my power steering faults - firstly doing absolutely jack, then going for the fuse, then finally having to bite the bullet and replace the controller.

So, I would surmise that in fact your ECU was faulty from the start and that as the fault occurred within warranty, it should be repaced free of charge, even though the car is now technically out of warranty.

Just imagine - your gearbox was playing up and you booked it in to have it looked at only to be told that they couldn't fit you in for a fortnight, when your warranty has 10 days to run - would you expect to stump up for the parts? I wouldn't and I don't think you would either.

Say no to any 'goodwill' gesture, you're entitled to have this fault rectified free of charge - it's not your fault that the dealer couldn;t get to the root of the problem in time is it?

Hope this helps,

Mike
 

Rob Earl

Past Member
And if the garage give you any grief, phone Consumer Direct who will clarify what your legal standing is & tell you how to go about getting the desired result. They're usually pretty good..
 
Giles,

sorry to hear of all the problems you've been having; hope it gets sorted soon.

My particular problem, see post of 27th June above in this thread, did turn out to be the NOX sensor. Smith Knight Fay replaced it yesterday for £208. Here's hoping I see no more engine warning lights.
 

gilesf

Member
Hi John, Skipton, Redders,

I'm supposed to be picking the car up on the weekend, will give you an update next week as to how i all turns out.

Thanks for your posts and hopefully I'll have some positive news!!!

Thanks,
Giles
 

gilesf

Member
ECU Part Number

Hi everyone,

Just hoping someone can assist. Does anyone have a list of Audi part numbers? More specifically the part number for an A2 1.6 FSI ECU?

Thanks,
Giles
 
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