Can anyone help please?
i recently bought a late 2012 XF 2.2 litre, does anyone know howto permanantly disable the auto stop start? Its driving me mad!

 

You can disconnect the auxiliary battery if you really want it gone. It's not an elegant solution and obviously you'll have a dead aux battery going forward. Or you can ask your dealer. They have the ability to disable it through reprogramming your vehicle, but apparently very few will actually do so.

 

Thanks, it really does annoy me. Does the aux battery have any other function?

 

As far as I know it's just for the stop/start function. Many people choose not to replace the aux battery when it inevitably dies. They see it as a benefit.

Checkout this thread: https://www.jaguarforums.com/forum/x...f-xf-s-174715/

There's confusion in that thread over model years, but anything that refers to unplugging a black plastic connector is in reference to the x260 XF and anything about the aux/eco battery applies to yours.

 

This wrong. The dealer can't disable start/stop. It is a gas saving feature they used to get the EPA gas mileage rating. It will be a federal offense if any dealer does this.
Unhooking the battery is the way to go and there are no downside to doing this. No dash lights and no error codes.

Now be aware after a certain year Jaguar changed from using a 2nd battery to a Bat Cap system and we have not had anyone disable Start/Stop with this later system.
I have a 2014 XJR and it still has the 2 separate batteries.
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Start/stop is not mandated by law where I live thus there's no federal offense in disabling it. A VAP tune can also disable it. It absolutely is within the power of the dealer to disable the system via programming and a few people report that they've had it done.

This is no different than adding an aftermarket pulley or tune that lowers stated MPG. It's up to the end user.

The later systems without the second battery are even easier to disable if you read the thread I linked to above. Unplug one connection and that's it. 30 seconds if you know where to look.

 

Yeah the start/stop is a requirement of the manufacturer. Otherwise they would not have been able to install that little button to disable it every time you get in the car. ( That's what I do)

 

Thank you for your help!! i will give it a go and let you know.

 

You still don't get it?
This is an EPA mandated feature and no state can over rule the federal governments laws.
No dealer anywhere in the US can legally disable this.
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Well, somebody doesn't. Despite what you may have heard, this is not federally mandated and it is not a question of legality. The manufacturer chooses to use this feature in order to look better on fuel economy ratings, and they (the manufacturer, not any government) do not allow their dealers to modify it (although some will).

 

Show me the regulations (Sorry I work with federal regulations every day and have a link to the CFR on my desktop)

. You can see here consumers are not mentioned.

Manufacturers use whatever they need to make CAFE standards, ti snot like Catalytic converters that have to be installed and maintained to meet smog control. that is a responsibilty of the consumer.
When you get smog tested do they check your stop start? Of course not.

 

It is in no way mandated. It is a tool that the manufacturer uses to lower their overall brand MPG rating. It is not required to be maintained by the end user.

 

I disconnected the aux battery and all is working fine! No annoying stop start! Thank you XFJoe.

 

Glad to hear it! It made mine much more enjoyable to drive.