cliffcoggin

The point about old batteries is not so much their remaining capacity in terms of ampere-hours; it is more to do with internal faults that can interfere with the car's ECU. I am no electrician so I can not explain it in any more detail, but I am aware that batteries can suffer internal short circuits, sulphating of the electrodes in lead/acid cells, sediment at the bottom, and other faults that are not apparent to the ordinary user without special test equipment. Can you get the battery tested by an auto electrician? When I last had a new battery fitted as a result of similar false warning lights, loss of turbo, and loss of cruise control, I was told it had to be "coded" to the car. Being a natural cynic, that phrase instantly made me suspicious that I was being told BS. Even though the new battery cured all the problems with the car I still don't know whether to believe this coding story.

You mentioned at the start that you had a faulty battery which you dealt with. Did you fit a new battery or a secondhand one? Old batteries can cause a variety of apparently unrelated faults even when the alternator is putting out a good charge.

Good point about scrap yard absences. I too am sceptical of error code readers. I see many examples of false diagnoses on this forum, though I am too old school to have personal experience of them.

Rob. In regard to question 1, the first press of the key fob button unlocks the driver's door only, a second press within five seconds of the first unlocks all the other doors.

None of us doubt how easy it is to change that switch. The important question is whether you simply struck lucky in choosing that option from the many possible causes of an ESP warning, or did you know it to be a particular weak point of the A3?

Ryan. Colourless fumes or slightly grey smoke would be just an exhaust leak, but white smoke suggests coolant is mixed with exhaust fumes. Is the water level dropping? I seem to recall that the EGR (exhaust gas recirculation) valve is water cooled, which might be the source. Not sure on this point.

Getting rid of the warnings and resetting the codes is pointless unless you cure the fault that is causing them. If the yellow ESP light has been on since you bought the car that is the first thing to investigate. It is not something that can be diagnosed on a forum unfortunately because so many circuits are linked to it. You need professional help to solve the problem.

It's impossible to guess with such meagre information. See this for suggestions: http://www.auditech.org/acont-654.html

Fair enough. It does seem that LEDs are brighter.

I am curious to know why you want to do that?

I have feeling that the discussion of viscosities etc. is a red herring in this instance, and that there is an underlying problem that has not been solved. Let me explain. The oil pump should be capable of creating much more pressure than is required by the engine in order that the pressure is adequate at idling speed, no matter what viscosity of oil is used, any excess pressure as the engine speed rises being bled off by a pressure relief valve to maintain a more or less constant pressure in the oil galleries. In this case the pressure is not high enough to prevent the warning light showing, so the question becomes why that should be. The possibilities that occur to me are: [1] The oil pump is worn. [2] The pressure relief valve is faulty. [3] The engine bearings are worn. [4] The pressure switch is faulty. [5] The pump is sucking in air. Unless anybody can add to that list, or disprove my logic, the problem must be one of those five things. I know that some of those parts have been renewed, but even new parts can be faulty or incorrect for that particular vehicle. Furthermore I see no investigation reported yet of items [3] and [5]. What say you chaps?

Not necessarily all the time, however smoking is always worse when the engine is working hard. A dense cloud of black smoke is not the result of removing the EGR alone, something else is wrong. Perhaps the injectors, perhaps engine wear, perhaps the remapping, but whatever the cause its sounds as if it will fail an MOT because of the emissions so you need to resolve it. My natural cynicism would make me suspicious of any engine that had been modified in the way yours has. I suggest you get it tested and hope the solution is not expensive.

Blue smoke is a sign of oil burning, usually because the rings/bores are worn. Does it smoke under hard acceleration? Erratic idling may be part of the same problem if the engine is clapped out and has lost compression, or it may be unrelated.

Fair enough, it must be something else. The advice from your garage is utter nonsense. Soot can not be created or deposited in a non running engine.

A faulty battery can cause those sort of problems, even if the alternator is putting out a good current. Is the engine turning slowly when cranking the starter? Do you have to keep the battery topped up on a mains charger? Is the acid level up to the mark?

James. If these 13-15 year old cars you are looking at are still running I'd say they have all proven their reliability. How long are you expecting your purchase to keep going? Personally I can vouch for my own 2007 2.0 TDI, but then I have zero experience of other engines for comparison, so don't rely on my opinion.

Good day Kevin. Bearing in mind that I know nothing about audio, the only the thing I can imagine that would interfere with radio but not disc player would be the aerial. Perhaps check the connection at the back of the set to start with.

I think I recall somebody solving that problem a year or two back. Have you looked through old posts of this forum?

For clarification Martin, is the juddering when you are slipping the clutch, during take off for example, or when it is fully engaged? If the former I agree with Gareth; if the latter something else is wrong.

What engine? What fuel? What transmission? Give us a clue Martin.

Well I could see no picture in the video, there was only a faint sound; and telling me the smoke looks like vaping means nothing to me. In the absence of any evidence to the contrary, such as coolant loss, sooty plugs, blue colour in the smoke, or a road test, I would go with the garage assessment of steam condensing in cold air. (Water is a product of the combustion process.) Sorry Will, but you have not convinced there is anything wrong. Can you supply any other information?

Revving the engine whilst parked outside your house is not the same as accelerating hard. Take it to a suitable road where you can accelerate with your foot to the floor for at least five seconds, and report the smoke appearance. You have not mentioned any garage until now. Tell us more.

If you can see the smoke it must have a colour. Describe it.

Is the smoke white/grey or blue? Does it get worse during hard acceleration? Is there a thick coat of soot on the spark plugs?

And the injectors?