I have a 20 plate 35tfsi Black Edition sline Q2. The stop/start never works, it always shows a line thru the symbol on the dash but now I’m getting occasional EPC warning symbol shortly after starting the engine and driving off. If I stop and restart the EPC clears but stop/start is still not working. I have checked the battery and getting 12.5v without engine running. Any ideas before I shower it in money please ? 

2 hours ago, Weeder said:

I have a 20 plate 35tfsi Black Edition sline Q2. The stop/start never works, it always shows a line thru the symbol on the dash but now I’m getting occasional EPC warning symbol shortly after starting the engine and driving off. If I stop and restart the EPC clears but stop/start is still not working. I have checked the battery and getting 12.5v without engine running. Any ideas before I shower it in money please ? 

Hi get the car plugged in and scanned for faults that should illuminate the problem.

Steve.

Hi Steve, thanks for the reply. Will get it sorted and forward any findings.

Just got the car back after 1st mot, after doing a diagnostic I was told there was only 1 fault relating to fuel pressure which was cleared. Driving back the stop/start is still not working ? Started the car yesterday and the EPC light stayed on with a stop/start warning. Turned engine off, restart and all cleared again. Not too bothered about stop/start not working as I tend to turn it off in town but it’s the Epc that’s a concern. Had to drive it with the warning on recently because I couldn’t stop, it ran ok, not in limp mode or anything. Help !

Hello Mike, 

All other things being serviceable, the failure of the stop start system is usually associated with a below par battery. Appreciating you have check your battery voltage, but if that was with a multi meter, then that no- load test is almost meaningless. 
Stray warning light issues can also be characteristic of battery issues. Yes, I know the car starts well, so it is assumed that the battery must be OK, but the battery condition monitor will know differently! 
Even quite sophisticated battery test test equipment may not test all of the parameters monitored, so again beware of testing with ‘outdated testers’. 
A new battery - if needed - will need coding to the car. 
Kind regards,

Gareth. 

Hi Gareth thanks for the fast reply, appreciate it. Yes I put a multimeter on the battery and got 12.5 v while engine off and assumed all ok. I know these things happen but would you expect a 3 yr old battery on a 27k miles car to start to fail already ? When you say “coded” do you mean Audi have to do it ? 
Mike

Hello Mike,

Would I be surprised that a 3 year old 27K battery on a s/s equipped car is starting to fail? - No I wouldn’t, based on hard experience of non-Audis doing that just out side the 3 year warranty, and particularly since your car is likely to have sat around unused for possibly months during Covid component supply issues. 
As said, simply testing battery voltage with a multimeter is meaningless. 
Yes, coding will necessitate diagnostics generally only held by main dealers and independents. 
Kind regards,

Gareth. 

Gareth

Thanks for your time and advice, very helpful. When it gets worse I will arrange a new battery.

Mike

10 minutes ago, Weeder said:

Gareth

Thanks for your time and advice, very helpful. When it gets worse I will arrange a new battery.

Mike

Hi if you go to Halfords and buy a battery they also have the facilities to re code it to the car, come to that most high end independents can do exactly the same as now most of them have the new kit out that pairs any battery with any car, I did my mates BMW with an Autel unit we borrowed from a garage 900yds from where he lives.

Steve.

Finally had a new battery fitted, the car was throwing up all sorts of errors on the dash, ‘ put in P or N to start’ when it already was and clicking on the key several times before actually turning over. Seems to be sorted apart from a ‘fuel pressure fault’ which only appears in a diagnostic and keeps returning after being cleared. Had it booked in at an Audi dealer but in a nutshell they let me down with no apology so got back in car and drove home, 60 mile round trip wasted. Car drives fine ( start/stop works) . Local mechanic is unable to narrow down the fault and it was him who suggested Audi. Any ideas what to do now ?

Thanks in advance

You were lucky to keep the car running for two years with a defective battery. You would not believe the number of members here who will not accept that a battery can be faulty if it starts the car or still has over 12 volts.

Possibly the fuel pressure message is genuine. Consider taking the car to a VAG specialist rather than an Audi dealer for diagnosis and repair.

Cliffcoggin,

Thanks for the reply, bit confused though, what is the difference between an Audi tech and a VAG tech ? 

£££££s 

Sorry Mike, I meant to write independant VAG specialist as opposed to Audi dealer. It was getting late in the evening.

Cliff,

Thanks, got it booked in with independent that advertises “ dealer level diagnostic”. We’ll see what they find tomorrow. Fingers crossed !!

Please let us know the outcome.

1 minute ago, Weeder said:

Cliff,

Thanks, got it booked in with independent that advertises “ dealer level diagnostic”. We’ll see what they find tomorrow. Fingers crossed !!

Hi was the new battery coded to the car?, that would explain the lights on the dash if not, the low pressure fuel pump is probably he culprit for the fault, get them to check the live data on the pump when idling if its high it means the pump is struggling to keep up the pressure and is on its way out.

Steve.

Steve,

Yes battery was coded to car and all is well at present, no EPC or random messages. Will know tomorrow if “fuel” fault is still there.

Just back from garage, really impressed with them (E M Hughes. Oswestry) Basically they have cleared the code and it never reappeared. Fuel pressure lower than it should be but because it hasn’t lit an alarm on screen it’s within tolerance. Suggested driving it and if warning comes on or car cuts out or any other niggles then will have to check fuel flows to determine where the actual problem is. Could be fuel pump, pressure sensor or even a weeping injector. All that cost £24, unreal. He did suggest changing to E5 fuel or additives.