Audi Q5 losing power

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My Audi Q5 whilst travelling today suddenly lost power although the engine continued to run.

I managed to freewheel downhill into a safe space ,turned the engine off and restarted it, and I was able to continue my journey.

But the same thing happened again a total of 4 times during the 7 mile journey.

I reached my destination but have left the car there.

I notice when I turn the engine on I am given the message “Start-stop system:system fault.Function unavailable”

Any help or suggestions much appreciated!

Kind Regards,

[Magnet]

Hello John, 

Stop/start not working can be, and usually is, associated with a failing battery, and this is what I would first be wanting to check. The fact that the car still starts reasonably well, is not indicative of a serviceable battery, since the battery’s serviceability is continually monitored, and functions will start shut down as certain parameters are not met. 
The loss of power may (in caps) also be linked to this, but that would be a guess. 
If the battery needs to be replaced then I would only buy one by Varta/Bosch in their 5 year warranty range. These are available mail order from specialist suppliers at competitive prices. Buy once and wisely.

Kind regards,

Gareth. 

[Stevey Y]

Hi as Gareth said its most likely the battery, it is a feature of AGM batteries that the stop start will not function as it draws massive amounts of amperage every time it kicks in so as the battery gets older it can do without the extra grief, the sad fact of the matter is stop start really is not that efficient in cutting emissions as every time you start up again the PCM goes through a slight enrichment procedure to make sure the engine starts, more fuel extra emissions, I just turn mine off when I start up and eventually there is a process on my diagnostic software to disable stop/start which I intend to use, the only real benefit of this particular technology is that it makes more money for the dealerships replacing starter motors and worse case scenarios DMFs because its creamed the ring gear  in record time.

Steve.

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Dear Gareth and Steve,

Thank You for your prompt and detailed replies.

There is a warning light showing on the car dashboard (please see the picture) and the local garage who service and repair the vehicle thought was due to a faulty battery, and so replaced it with a Yuasa YBX 2019 .The car is a 2013 model. The light however has not disappeared and the garage tell me that I need a new sensor which they have ordered.

I find it alarming that the car can suddenly and completely lose power - I was only doing about 15 miles per hour on a quiet country lane at the time - but it would have been a different (dangerous) story if say this happened on the motorway. 

I am not particularly bothered about the "stop-start" ,as Steve suggests I have always been sceptical as to whether it does help the environment - but I am concerned about the complete loss of power.

I don't suppose the catalytic converter would have anything to do with it? - as you have probably guessed I am not particularly mechanically minded.

Kind Regards,

John

 

 

[Magnet]

Thanks John,

Yuasa YBX 2019? You would need to double check that this is the correct specified battery for the car - I haven’t checked. 
It’s also possible (in caps) that the new battery would need coding to the car, otherwise the battery condition monitor (if fitted back in 2013?) may be treating the battery as it was ‘conditioned’ to do with the old battery. 

Whether this has anything to do with your loss of power?? - but I would certainly not be wanting to ignore confirmation of both the above. 
Yuasa battery ??  Would not have been my first choice, but…..

Kind regards,

Gareth. 

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Gareth,

Again thank you for your prompt reply.

I will check whether the Yuasa battery is suitable for the car - I suppose calling the Audi dealer would be the best way to do this.

As far as coding the new battery to the car, is this something that can be done from the dashboard? ,or does it need to be done professionally using a device of some sort? - I suppose I could ask the Audi dealer at the same time as when I check the battery.

Kind Regards,

John
 

 

[Stevey Y]

Hi Yuasa are a premium battery they are used on practically every Japanese motor cycle built and the American military use them on some of their vehicles, you have to register the battery with the BEM module this is done with a diagnostic platform VCDS or Snap on.

Steve.

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Dear Stevey Y,

Sorry I am not mechanically minded - the BEM module and diagnostic platforms VCDS or Snap On mean nothing to me.Is this something the garage should have done when they fitted the battery?

Also what is the purpose of the warning light on the dashboard? - please see initial picture.

Kind Regards,

John

 

 

 

 

 

 

 

 

 

[Steve Q]

To jump on this, yes the garage should program the battery to the car. Also the yellow light on the dash is the engine management light. 

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Thank You.

The Local Garage have informed me that the catalytic converter needs replacing and this is causing the engine to lose power.

The estimate for this is about £2,500 - which is a similar figure quoted by Audi plus a £200 diagnosis fee to satisfy themselves that this is actually the problem.

Bit of a dilemma here - as the car according to the local garage a 2013 Audi Q5 with 86,000 miles on the clock is only worth (market price) about £11,000 and in reality less with a faulty catalytic converter.

So, I am deciding whether to offer it in part exchange for a new vehicle, or pay for the repair.

 

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I have booked a diagnostic test with Audi but the local garage now think it may be the ECU - so we shall see!

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I have spoken to the Audi garage and they have said the car is probably going into "Limp Mode" whatever that is!

The diagnostic test is tomorrow.

Regards,