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AudiDoc
AudiDoc, Independent Audi Shop Owner
Category: Audi
Satisfied Customers: 6457
Experience:  I've been working on Audis since I was 18 and own an independent Audi repair and performance shop
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Audi S6 Avant: I have a 2003 Audi S6 Avant 4.2 L V-8 Wagon

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I have a 2003 Audi S6 Avant 4.2 L V-8 Wagon and I am having problems with it starting after I have driven it for a couple miles and turn it off then come back 2 hours later and it won't start. I had it towed to my mechanic's garage and then next morning he said it promptly started and every time after it had started yet he had not driven it then turned it off, then tried re-starting it. The diagnostics says only epc as a problem but my mechanic says he has checked that and it's not the problem. Everything else checks out oil, fuel, electrical etc. help me I just bought this and have no idea what to do nor do i know about the lemon laws in P.A. Help me.
Sincerely, XXXXX XXXXX

AudiDoc :

Hello, I'm Jason. I will do my best to answer your question quickly and accurately using the information you have provided.

AudiDoc :

Ok, first, most important question back to you. When it's in the state of not starting, does the engine actually turn over, or does nothing happen at all?

Customer:

yes it turns over absolutely and the battery has plenty of power . I just bought this wagan for my pregnant wife about 3 weeks ago so this is new to us

AudiDoc :

Ok, now I need to ask about the basics, and I'll get onto the EPC issue in a bit...

AudiDoc :

So right now, every time your mechanic has checked it, it starts fine?

AudiDoc :

And I need to know if your mechanic is Audi or Euro-specific

AudiDoc :

or more of a general shop

Customer:

yes however he has not test driven it

Customer:

he is very keen with foreign cars in general especially german and japanese

AudiDoc :

ok, so the test drive is pretty important, since the problem happened after you drove it. We need to be able to narrow down whether this is a fuel or spark issue

AudiDoc :

If fuel pressure is lacking, I'd suspect a pump that is starting to fail....

Customer:

foreign his customers drive up to 3 hours away because he is honest but i think he might be over his head on this one

AudiDoc :

I've got folks who cross borders, so understood

AudiDoc :

I'm assuming that he's using the VAG-COM/VCDS scan tool

AudiDoc :

now, I'm questioning his dismissal of the EPC code

AudiDoc :

since EPC is throttle control

Customer:

that's just it it has two internal diagnostic tools within itself the fuel pressure reads fine as well as the electrical

Customer:

It was last owned by an audi tech who changed the oil every 3 000 etc. who claims this is something he never had a problem with

Customer:

Though I have been lied to before

AudiDoc :

This one is pretty tough to try to diagnose remotely...especially without a list of fault codes

AudiDoc :

I'd start suspecting a crankshaft position sensor, which doesn't often leave codes behind

AudiDoc :

but that's somewhat rare with this engine

Customer:

say there were no fault codes but the epc what then?

AudiDoc :

well, if there is an EPC fault, that's a fault code

AudiDoc :

hence my confusion

AudiDoc :

one moment....away from the keyboard

Customer:

he say's that he has been using castrol edge w/spt,5W40 is this the correct oil for this car because if it is not synthetic could it could lead to clogging, etc.

Customer:

if

Customer:

if

Customer:

if this is so what type of synt

Customer:

thetic oil should i be using

AudiDoc :

Oil won't be the problem here

AudiDoc :

I always use Motul VW/Audi specific oil in these

AudiDoc :

for what it's worth

AudiDoc :

but that won't affect starting

AudiDoc :

Really, the EPC codes are important, and catching the starting problem when it's happening, to determine if there is a lack of fuel or lack of spark is key

AudiDoc :

If lack of fuel, time to check the fuel pump relay, but if that fails, it will usually leave codes behind.

AudiDoc :

If lack of spark, I'd really suspect a bad crankshaft position sensor

Customer:

in either worst case scenario what would be the answer?

AudiDoc :

fuel pump relay, fuel pump or crank sensor are my first three thoughts

AudiDoc :

but again, this is without knowledge of the stored EPC codes

AudiDoc :

While I'd like to offer a magic bullet answer, obviously some of these issues require some pretty in-depth diagnostic strategies

AudiDoc :

But hopefully the session here has armed you with some information at least

Customer:

when i get the codes and find out more monday how can i get ahold of you for more answers?

AudiDoc :

Even after rating the session, you will get a link in your email to respond to me if needed

AudiDoc :

I will also give you the link to my direct page here

Customer:

could it be a problem with the gas tank vacume sensor or something of the like?

AudiDoc :

gas tank vacuum sensor?

AudiDoc :

no sort of EVAP emissions problems will cause the car to not start

AudiDoc :

and if there was an EVAP problem, there would be a fault code indicating such

Customer:

yes or some gas tank sensor could it maybe be a corroded wire on the starter? or would it show up on the electric diagnostics?

AudiDoc :

Again, there is no gas tank sensor. Also if there was a corroded starter wire, the engine would not spin over

AudiDoc :

The 3 things I mentioned are the important ones.

AudiDoc :

You will still be able to reply, but I do need to sign off for the night.

Customer:

thanks

AudiDoc :

I'm switching this over to email format now, so we can keep in touch if needed

AudiDoc and other Audi Specialists are ready to help you

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