Intermittent start/stop system fault

[alFR]

A couple of times (once about 2 weeks ago and once today) I've had a fault on the start/stop system, with the "system unavailable - contact workshop" message on the DIS. Turning the car off and on again has cleared it both times. I'll get the dealer to look at it at some point (especially if it does it more often / repeatedly or if a restart stops clearing it) but wondered if anyone else has had the same thing?

 

[cuke2u]

Nope, hopefully your car systems has stored some errors codes or the dealership might say they can't find anything...

 

[DarGri]

A couple of times (once about 2 weeks ago and once today) I've had a fault on the start/stop system, with the "system unavailable - contact workshop" message on the DIS. Turning the car off and on again has cleared it both times. I'll get the dealer to look at it at some point (especially if it does it more often / repeatedly or if a restart stops clearing it) but wondered if anyone else has had the same thing?

Hi, did you ever get this looked at?

I've had this crop up maybe 6-8 times this last week "Drive System Fault/Start Stop Unavailable, contact workshop"

Car is going in on Thursday but thought I'd ask. Cheers.

 

[alFR]

Hi,

Sorry for the late reply... Was going to bump this thread anyway as the issue isn't resolved and I wanted to see if anyone else had any experience/advice.

Car went in to Audi in January, they diagnosed a static fault on the oil pressure sensor which was duly changed. Car was fine for a couple of weeks, then came up with the same fault again (about 3 times in a week). Rang and got it booked in for this week (about 3 weeks delay due to courtesy car availability) and it did it once more between me booking it in and now. This time Audi (dealer and UK technical who they sent the logs to) can't find anything wrong with it, they say that despite there being a fault displayed to me on the dash the computer hasn't logged any faults. Their plan is:

• I get the car back and keep a log of when the car does the fault over the next month or so, logging temperature / weather conditions / time of day etc. to see if they can establish a pattern.
• They have it in for a week after that so they can do more tests / randomly start replacing stuff to see if it fixes it (my interpretation, not exactly what they said) / give it to one of the techs to use as his car for the week to see if he can reproduce the fault.

The logging is maybe a good idea, but overall I'm not happy with the plan: even if they have the car for a week it might well not do it during that time (it has gone more than a week between showing the fault in the past) and I'm certainly not happy with one of their techs driving round in my car for a week. I appreciate that intermittent faults can be hard to pin down, but I'm struggling to understand why there's nothing in the logs. At the moment I intend to get the car back today, keep a log of the fault as requested and speak to them / email them with the data in a few weeks and ask them to come up with a better plan. I am also considering getting VCDS or similar to see if I can plug it into the car myself while it's exhibiting the fault and look for error codes: anyone got any advice on what software might be best for that?

DarGri, what happened with yours?

 

[DarGri]

@aIFR

Mine was diagnosed as having a faulty boost pressure sensor, car was fine for about a month and then the fault came up again intermittently over a couple of days. Took it back in and the techs seem to think it was an EGR fault, it's due to go back in for further investigation on 4/4/17 but funnily enough the fault hasn't reoccurred yet.

It's getting its first service while it's in too so who knows what they'll find (if anything)

 

[alFR]

Interesting, another sensor fault repaired & issue persisting afterwards - different sensor but otherwise same story as mine. Forgive my ignorance, but what's the EGR?

 

[DarGri]

Interesting, another sensor fault repaired & issue persisting afterwards - different sensor but otherwise same story as mine. Forgive my ignorance, but what's the EGR?

Exhaust Gas Recirculation valve, basically it diverts exhaust gas back into the intake to control emissions.

 

[alFR]

Thanks! If you could update on what happens after yours has been in that would be great. I'll update if I learn anything more...

 

[ANX]

Yes, had stop start give up in a similar manner with similar error on dash.

Whilst my car logged an ECU failure, Audi where seemingly unable to give a satisfactory diagnosis and simply pulled the battery and reset the fault codes. having no faith in that fix I just permanently disable stop/start. Not great..

Are we all TDI owners?

Thread http://www.audi-sport.net/xf/threads/ecm-pcm-fault-code.311587/#post-2944204

 

[alFR]

Didn't yours stop and refuse to start again though? Mine won't stop when it's showing the fault. Better than not starting at least!

It is a TDI though, yes, as is DarGri's. My suspicion (totally un-educated though it is) is that it's either a software bug somewhere that's reporting an error when the hardware's actually fine or some other problem with the onboard computer: that would explain why there's nothing in the logs. Be interesting to see what comes of our further investigations anyway - at least the car is fully driveable in the meantime & so far I have been able to clear the fault easily by turning the ignition off and on again.

 

[ANX]

Ah yes, wrong end of the stick then. stop/start vs start/stop perhaps! Still.. annoying problems with a somewhat annoying system. I will follow with interest regardless and hope you have better luck getting to root cause...!

'Luckily' I spend most of my time crawling along the m6 and don't see a traffic light until 30 miles into my 35 mile journey to work - turning it off is no great shakes.