Hi, recently purchased Jaguar XF (2012) from a dealer about 5 weeks ago. Didn't think the car had start/stop because I drove it for about 4 weeks before that started happening.
Went back to dealership and tech bloke said ECO would kick in if battery was loaded due to air con on and radio on etc etc. I said to him why has it taken 4 weeks to come on
if I have been using air con & radio etc? He explained a lot about second battery needed to be a certain charge level etc but it still doesn't make any logical sense to me.
Then found out that there is an ECO button on dash, So I thought cool will use that to switch it off every drive cycle. Upshot is I did that a couple of times and everything was ok
i.e. no more stop/start.
Now I am not using the ECO button and it is not Stop/starting!! getting bit confused with all this, is there a problem with the car or is this normal?
If anyone can shed any light I would be most grateful...

 

My wife's 13 3.0 didn't work hardly at all when we got it. I think it might have stopped/started 5 times in 6 months. She got the same standard I didn't do anything but I'll talk my way out of looking at it the first time in then the second time it was in they did some digging and found that the computer needed an updated reflash as it wasn't reading the 02 sensors right. Now it stops/starts at nearly every light. Careful what you wish for.

 

 

Everything should be fine. Most likely the battery isn't up to it. Also possible that the secondary battery has a loose connection

Go to auto zone or equivalent and have them test the battery (both if your stop start is the one with a secondary battery). They will do it for free. If it's weak just replace it. It will save you a lot of other electrical gremlins too - they are quite sensitive to battery levels

 

My wife was told (second hand to me from a woman who knows little about cars) that the dealer told her that it was an issue with the computer interfacing with the heated 02 sensor so the car was not thinkng it was warmed up enough for the start/stop to work. She said it was a tsb so maybe you could have a look for it and see if it would cause the car to run rich longer and cook the cats over the long term.

 

Thanks for replies Britcars & Trevortasmin
"she said it was a tsb?" what is that Trevortasmin?

 

Technical Service Bullitin.

 

Please ignore the woman and the nonsense about the O2 sensor.
The tech gave you the correct answer and I don't know why you don't think it makes sense?
There is no software update and you can't have the dealer turn it off. It's part of how Jaguar got the government mileage rating and is illegal for the dealer to tamper with that

If the BMS (Battery Monitor System) does not think the small battery is charged enough you will never have start/stop. As you drive around and recharge both batteries the start/stop function will start up again. If you don't want start/stop then disconnect the small battery in the trunk and you will never see it again.
It will not set any error code.

If you are concerned that the start/stop is not working right then check the condition of the small battery. Remember there are 2 different systems too.
Early setup they used two separate batteries. Then they dropped the second small battery and went to a large capacitor type setup. With that system we don't know if unhooking it will work or not?
Maybe?
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So you are saying the dealer lied to my wife and bingo the start/stop magically started working without anything else other than a trip to the dealer and nothing replaced? Considering they said there was a tsb for it I would think his dealer should be able to look for it based on that. Now hers is a 13 with the worlds worst sounding engine in it the v6 but still. It went in because it wasn't working and came out working after they said they did a software update so the system was better understanding the parameters of the 02 sensors. I don't see them making a story up. LOL

 

Yes.
Please post this TSB so the rest of us can learn?
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I don't know where you are located, but in the US the eco/start/stop functionality wasn't released till 2013 MY.

 

Technical Service Bulletin.

 

Each time you start the car, the ECO is on. If you don't want it to activate, you must press the ECO button every time you start the car.

If you are doing anything that is taxing the car, the ECO will not kick in. If my A/C or Heat fan is set to speed 4 or higher, the ECO will not kick in. If my car is cold (recent start), the ECO will not kick in. My car is a 2015 with original batteries that are still strong, so I've not experienced a weak battery preventing the ECO.

So, if you hop in the car with the AC or Heat cranking, the ECO will never kick in. If you don't run them or shut them down, then you'll start getting the ECO triggering once the car has warmed up.

 

How do I know if my 2012 has this?

 

It should have an ECO button, 2012 MY don't have them in the US as it was introduced in 2013 MY cars.

 

Yes and look in the trunk for 2 batteries.
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Had my MY13 XF 2.2d for three weeks and never had the Auto Stop/Start operate once yet, but with the weather being what it is the A/C is always on and also the radio/audio so no surprise that it has not triggered. Must try a run with them switched off just to satisfy me that it is working. I had a brand new Hired VW Golf with Eco stop/start recently on holiday in Italy which was certainly not as intelligent as this as it cut out at every stop irrespective of what systems were operating, although it sometimes almost instantaneously started again at times.

 

I'm glad my 2010 XF doesn't have stop/start. My wife's 2018 MB E400 wagon has it and we turned it off permanently by buying a module from someone on Ebay. Otherwise, it turns on each time you start the car unless you press the Eco Off button. This way, it remembers that you turned it off from one start to the next.

 

Well it is obviously working OK, coming home late last night when it was cooler and the AC was just ticking over at the end of a 45min journey mainly on Motorway, stopped at a crossroads about 300m from home and engine stopped and green ECO light came on, started up when I took my foot off the brake so appears to be working as designed. Just over three weeks of driving and this is the first activation, obviously a much more intelligent system than that was fitted to the VW Golf I had on hire in Italy.

 

what volts should i check the smaller battery for?
i have charged the big battery but not too sure how to check the health of the smaller battery.