Faulty automatic light sensor?

[andyjgw]

Hi

Looking at a fantastic 55-plate A4 3.0 tdi quattro s-line last night, the only thing that's of worry is that the owner says it needs a new light sensor. He demonstrated this by turning the light switch to "Auto" and we could see the headlights flickering against the garage door. I reckoned I'd just do without Auto, but he says it affects the lights even when they're proper-on, if you know what I mean?

Read around on the site and it appears the sensor for this is in the rear-view mirror? Does anyone know what all this entails, and is the diagnosis of it being the sensor correct? Don't want to be buying a car where what appears to be a simple fault results in half the dashboard needing removed and some horrifically over-complicated and expensive part needing replaced. Didn't see anything about it in googling so far - can anyone help? The only other thing outstanding on it is there's an 80k service looming, I looked and it appears to be just "check more things" so not overly worried about that, unless anyone knows different?

Would really appreciate any quick feedback on the lights issue as may have to make a decision on it today.

Thanks

A

[MarkTM]

If affected when 'proper on' doesn't sound like the daylight sensor.

Any chance of getting the car scanned with VCDS?

[andyjgw]

Thanks Mark, that's what had me worried. He says I can get a mechanic friend of mine to check it out if I want, so I think I'll go down that route. Tragically, he has someone else coming to see it today and with my luck, this will all be off the table by the time I could get my mate involved... Not sure whether to hope it goes that way or not.. there are other cars out there of course, but this is local, fairly priced given its issues and niiiiice.... ;-)

Any other ideas what might be causing flickering lights ?

[MarkTM]

If no errors on the dash/DIS then my best guess would be a faulty ground/earth.

You've not stated if it's ALL lights or just the front ones/headlights/sidelights, also if the car has Xenon lights, failing xenon's can display a flickering behaviour and if they are the original ones fitted to the car then a possibility. If not Xenon then discount that.

But until you get a scan it's going to be guesswork.

[andyjgw]

I like the idea of Xeon headlamps causing it - is that a full replacement job, and are they expensive ?

Is VCDS a dealer-only thing, or perhaps somebody knows someone in Inverness who can do it privately? Checked out the Ross-Tech stuff, looks expensive..

Any apps on Android that might be suitable to give me enough idea perhaps? I have a Bluetooth OBD-II adapter that works with Torque on my phone.. Just trying to think of ways I can nail this on a Sunday

Thanks for the help Mark, very much appreciated.

[MarkTM]

Andy, maybe but you've still not said if ALL the lights or just the headlights, or can't you remember.

I bought my car in 2012 and VCDS in 2013, it has paid for itself in the 13 months I've had it and takes a lot of the guesswork out of diagnosing faults etc.

And think with your flickering lights you may be able to hire your car out for outside disco's!!

[andyjgw]

Now it's occurred to me to check for "flickering headlights" instead of "faulty light sensor", there's a lot more info showing up.. Sounds like this may be a common problem after all.. Please Help Flickering Headlights - Page 4

[MarkTM]

Perhaps appropriate if you definately know that car has Xenons.

The Hella ballasts are about £70 each on Ebay used or £300 each from Audi.

Probs best to let this one go, I travelled over 100 miles each way to see my car, but appreciate you may be a little stuck for choice up in Inverness

[andyjgw]

Thanks Mark

Think that's the conclusion I'm coming to. Herself lives in Edinburgh tho and we don't mind a bit of travel so will just keep an eye out. Still got the option of asking my mate to check it out so if it doesn't sell, I might go down that route.

It's been remapped as well and really flies. Smart car and unusual colour so was pretty tempting. Cheers for the advice

(re the all-or-front lights, I've asked the owner but no reply yet. Tail light also out which the dash is alerting on - possibly this is masking the true error for the rest of it...)

[MarkTM]

Remapped...can see the temptation!

When I bought my Jaguar in 2005 I flew to Newcastle and drove it back, so circa 400 miles each way, but back then internal flights were a little cheaper than today.

Summer is the best time to buy a quattro as in colder months they tend to command higher prices.

A real shame as I was due to be up in Glasgow for the Merchant City Festival this weekend (been for the last 5yrs) but the Commonwealth Games meant I couldn't afford the price of hotels. If I had would have been happy to pop over to Embra and scan it for you .