cliffcoggin

Not an identical experience but close enough that it may be relevent. Occasionally mine (also a 2 litre diesel from 2007) would simultaneously show a brake warning light, lose cruise control, lose air con, lose radio presets, and go into limp mode. A few minutes rest restored normal operation. The cause was recognised by a local VAG specialist, who ignored all the false error codes, as a defective battery. Have you had any other strange electrical faults? Was the engine slow to crank over when starting last winter? How old is your battery?

What makes you believe that either the sensor or the cat is defective? Have you considered that there might be a fault with the engine?

Wes. From the limited description of the symptoms it's unlikely anybody can give a precise diagnosis because there are so many possible causes of the problem. Your best option is to have it tested professionally. You have not mentioned the mileage but a 15 year old car is no spring chicken, and should have a long service history. The lack of any such history looks very suspicious.

If the only recommended solution is a new roof, then you have nothing to lose by trying to glue it back. The bath sealant type of silicone mastic is a good adhesive if you can clamp the joint while it cures, though I have not used it for this particular repair. Be aware that many of those silicones are stabilised with acetic acid (vinegar), the fumes of which can corrode adjacent metal parts so ventilate well.

As the battery is only two years old it is unlikely to be the cause of the problems, though I would not entirely rule it out. In your position I would have it deep discharge tested just to be sure. If the faults lie elsewhere I doubt I can contribute anything useful so I shall leave it to others to assist.

If you want help with a fault you have to be precise in your description of it, and that does not always happen. For example we had a correspondant recently who did not know the difference between a tachometer and a speedometer. So I make no apology for questioning which particular light you wrote about. In an effort to be helpful I asked at the end of your previous topic about the battery. I have yet to read your answer.

There are many dashboard lights. Which particular one do you mean by "engine light"? Is this the same car you mentioned in your topics of April 17th and the one before that, and are you still taking it to the same cowboy garage for diagnosis?

That confims the clutch is slipping. If you are lucky it may just be a matter of adjustment; if you are unlucky you need a new clutch.

Another test is to find the "bite point" of the clutch. Apply the handbrake firmly, press the clutch pedal to the floor, engage first gear, open the throttle a little (1300 rpm approx,) and slowly raise the clutch pedal, noting the pedal height at which you can feel the clutch start to engage. That height should be around half up. If that bite point is much above half way there is something wrong with the clutch.

Sounds like the clutch is slipping.

I don't know the answer Dan, but I recall the question being asked a few times in the past. A look through the forum history may be helpful.

Whether it is a belt or a chain it needs to be looked at. If it fails it could wreck your engine.

I am not sure I fully understand the problem. Does the engine speed, as shown by the tachometer, truly go up and down, or is it just the indicator lights that are changing?

Glad to hear it. Confirmation of the solution would have been helpful to others in a similar situation.

None at all. I did not know of a primary air pump, let alone a secondary pump. Or have I misunderstood? The lack of punctuation makes it difficult sometimes.

Please confirm you are using an automatic gearbox.

Corrie. Did you find a solution, or did you concede defeat?

Craig. Did you find the leak? How did you rectify it?

Ben. Did Stevey's answer help? Have you resolved the problem?

Do you have a question?

Possibly the cam belt tensioner flopping around. How many miles since the cam belt was renewed? Or is it a chain drive?

How old is the battery Jim?

Thank you Roy. Evidently I am out of touch with modern developments, though modern may not be the best term to use considering the article was written ten years ago in USA, a country whose diesel development tended to be behind Europe. I have always avoided getting too involved in discussion of anything electronic because of my ignorance of the matter. I guess now it is time to realise my knowledge of modern engines is equally lacking.

Martin. So many correspondants here have reported glow plug faults from code readers that turned out to be entirely unrelated to glow plugs that I begin to wonder if "glow plug fault" is the default error mode for anything the readers do not understand. Even if there is a problem with the glow plugs you will not notice any difference in performance because the glow plugs do not operate when the engine is running. Their only role is to help start the engine in cold conditions by raising the temperature of the fuel/air mixture enough for auto ignition to occur.

Mmm. Cotes du Rhone I hope. Nothing but the best for an Audi.