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Hi Guys, can anyone help with this please? 

I went ou to the car today and the battery was dead flat, no idea why, not happened before. We connected a booster and fired it up, all OK except esp warning light is now on, pressing the ESP button has no effect. Car is now starting as normal.

 I've not driven it yet. Any ideas as to the reason for this and how to resolve it please?

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Hi Ken, 

Have you had the battery tested at all? 

I ask this because when a battery is failing it can cause all sorts of electrical faults can occur. If that's the case it would be worth replacing the battery. If the battery is fine then the next question that needs to be asked is why has your a4 gone flat? To answer this it might be worth you getting a diagnostic check carried out. 

It also might be worth you taking the car for a good drive to see if that resets the esp light and will give the battery some good charge. 

Sorry I can't help more.

Cheers :)

Steve 

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Hello Ken,

As Steve says, a battery check would be my first port of call - charge it up overnight (or at least by a continuous hour run) and get it checked at Halfords. If it's found to be suspect then you can of course buy a new one there, but I tend to buy from the specialist on line suppliers, by buying quality makes at reasonable prices. 

If the battery is found to be serviceable then come back and we can advise on assessing parasitic drains etc. 

Kind regards,

Gareth.

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OK, first of all, Thanks for the input, I apologise for the delay but due to weather etc I've not been able to do anything with the car.

The battery wad dead, we tried it again and it wouldn't even light the warning lights, we presumed the battery had failed, but we noticed that the electric fan kept intermittently switching on (must have been a little bit in the battery) even though the ignition was switched off. We thought it may be due to errors with battery being flat or something,  like the ESP light. 

Fitted a new battery today, car fired up ran great, problem solved, or so I thought.  During the evening a couple of hours after fitting the new battery,  I heard a noise outside, the electric fan was full on, I went to the car and as soon as I switched the ignition on the fan stopped. I unplugged the fan to stop it killing the new battery and now have to find the cause of this problem.  Could it ge the coolant temperature sensor? The ESP light went out when I drove the car.

 

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It definitely sounds as if you have a short somewhere in your electrical system, I would try starting it up, reconnecting the fan and going for a drive far enough to see if the temperature gauge is registering. Obviously if it's not working it could well be the coolant temperature sensor, if the gauge is registering it would suggest there's a short in the wiring for the fan that's draining your battery. In which case it's probably best to find someone with VCDS that can do a diagnostic check on it so you're not chasing your tail.

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The gauge is working as normal, disconnecting the fan hasn't affected it. According to some forum posts I've read, a faulty coolant temperature sensor can cause the fan to come on, but I would have thought this would only happen when the ignition is on. My first thought was like yours, a short or something. As soon as I turned the ignition on, the fan stopped.

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According to some further research it could be damp causing a short in the ecu, apparently a common fault.

Does anyone know if I can just replace the ecu? Or will reprogramming be necessary?  Or will it not recognise other parts?

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Hello Ken,

Sorry to hear of your problems. I would agree it could be the coolant temperature failing via. short or open circuit, since I believe this will then automatically set the fan to run since the ECU cannot sense the coolant temperature so it triggers the fan incase it is overheating. I also believe the fan will run (for a couple of minutes) after the ignition is switched off?? Continuously ?? - No, I would have thought. Other sensors may well trigger the fan. 

Result of An ECU problem? Possibly, that is a somewhat drastic diagnosis. To me, this needs to be plugged in, and the fault codes read before any more action is taken on guessing.

Things which appear complex can sometimes be quite simple. I have my fingers crossed for you Ken. 

Kind regards,

Gareth. 

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Thanks for the reply Gareth. I know yeah sometimes problems have a simple solution, the difficulty is in diagnosing the problem lol.

I would think that a short or problem with the ecu would cause more problems than the fan running. As for the coolant sensor,  again I wouldn't think it would have any affect with the ignition switched off. As it is, I've left the fan unplugged, its only the air con fan, which I dont use anyway.

The car died on me yesterday,  no fuel getting to the engine from the tank, so its now at the garage to be sorted.

When it comes back its going, first and last Audi I think, going back to Ford.

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On 3/13/2018 at 2:05 PM, KenL68 said:

Thanks for the reply Gareth. I know yeah sometimes problems have a simple solution, the difficulty is in diagnosing the problem lol.

I would think that a short or problem with the ecu would cause more problems than the fan running. As for the coolant sensor,  again I wouldn't think it would have any affect with the ignition switched off. As it is, I've left the fan unplugged, its only the air con fan, which I dont use anyway.

The car died on me yesterday,  no fuel getting to the engine from the tank, so its now at the garage to be sorted.

When it comes back its going, first and last Audi I think, going back to Ford.

I do hope the issue gets sorted Ken and sorry you've been put off the brand. 

Cheers

Steve

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