So AUDI A5 2015. 

1. left for 5 weeks came back to flat battery
2. charged battery and was OK for 3-4 days then flat again (10y old)
3. replaced battery with Tanya AGM
4. wouldn't start or turn over.
5. Lots of error codes
6. tried to clear using OBD 11 PRO but it couldn't connect. 
7. disconnected battery and temporarily joined the car cables together to discharge capacitor
8. tried a jump start
9. checked and cleaned battery terminals
10. temporarily removed the "shunt" connector from the negative

When I turn the key it just starts list code after code but Ive not seen an immobiliser code. 

Been fixing cars for 50 y but never have seen this before HELP 

Can you get a multimeter on the starter motor to see if it's getting power? Again, this time of year sorts the wheat from the chaff so to speak with weak or old batteries. Also use multimeter on new AGM battery to double check. I normally stick it on a trickle charger to top up before installing.

Hi did you code the new battery in when fitted, and was it any length of time before the change with the old unit flat, sounds like the Can gateway has thrown a hissy fit and shut itself down because at some point in the process it thinks its being stolen.

Steve.

Hi thanks for prompt responses. I can't easily get a multimeter on the starter motor but there is absolutely no noise from it eg solenoid clicking or anything. Battery has been charged and also jumped from another car to no avail.

I haven't coded in the battery as i don't have easy access to a device but Im told by several garages that the car should still start without doing that.

I agree though it looks like the car has shut down and locked me out. I can't even get it to a garage

sorry was about 10-14 days before new battery fitted

1 hour ago, mossymoo said:

sorry was about 10-14 days before new battery fitted

Hi an hour window on the change is as far as I would go when changing, see if you can find a mobile diagnostic specialist and explain your problem, chances are they will know a way around unlocking the can gateway, make sure the battery is fully charged, I have had your problem with OBD 11 but its always when its due a big fat update which they tend to do about twice every month so check that first.

Steve.

Just to close this down and thanks for everyones help. Had to call a breakdown service. They were unable to clear the ECR fault codes and car now to be transported from Skye to Inverness to the Audi dealer as they reckon no-one around here has the gear to fix it. Its my neighbours car and thankfully I have a VW. 

Really put me off Audi as a brand but Ill get over it

Jon

Skye to Inverness is a hell of a long journey. Have you looked for a mobile mechanic who might be able to come to you to do the job? I would not take Audi's word that such people don't exist. After all Audi has a vested interest in the matter.

I know 100miles each way. Decision taken out of my neighbours hands as he's got breakdown cover. 

1 hour ago, mossymoo said:

I know 100miles each way. Decision taken out of my neighbours hands as he's got breakdown cover. 

Hi Volkswagens are good I now run a Passat as a cab, still having counselling for the five years that I ran an A6, you would never believe that both cars originate from the same group.

Steve.

31 minutes ago, Stevey Y said:

Hi Volkswagens are good

Are VW electrics so different from Audi? I had assumed that both being part of VAG would mean almost identical electrical systems.

35 minutes ago, cliffcoggin said:

Are VW electrics so different from Audi? I had assumed that both being part of VAG would mean almost identical electrical systems.

Hi VW electrics are way more simple from software to the actual wiring of the vehicle, not sure if its because VW are cheaper to buy so they spend as little as necessary to maximise profits, with Audi who seem a law unto themselves the designation Premium Brand has been seen as a licence to inflict the most complicated systems on the owner therefore negating any possibility of DIY on even the most basic level without special tools and diagnostics, the Volkswagen dealers are a mile apart from Audi I recently enquired about a part which I bought to see how much the chrome trim was that fitted to it, turns out the trim was more expensive than the part so they gave me the part number and suggested I looked on line, £45 V £95 from the dealer, thats proper customer care.

Steve.

That surprises me Steve. Thanks for the information.

For what it’s worth:-

Our humble 2006 A3 has been in the family from new, and I used to get all parts for it from a Skoda dealer up North at very much discounted prices compared to the same part from Audi. 
This went on for years and I recall the dealer used to win Parts supplier of the year awards. Then it stopped!

Seems VAG wanted an extortionate amount of money annually to continue to supply the computerised cross reference numbers, brand to brand,

Good isn’t it. 

As I understand it ( and I’m open to contra opinion)  the trade discount on genuine Audi parts ex. dealers is now only 7%. Having said that, our Halfords club discount card now only entitles us to 7% off. Wow y! 
I guess in reality, the garages have to add more to the labour costs to make up for the shortfall on parts. We end up paying again.

Regards,

Gareth.