XF Start/Stop Not working

[marty599]

Hi all

A couple of moths ago my fan belt broke, battery went flat so had to be transported to the garage for repairs. The mechanic removed the battery to charge it. When I got the car back the start/stop did not work at all (Very frustrating) The mechanic could not find the fault at all! This morning I had the battery checked by someone else and he noticed that the sensor that is in the boot was disconnected, he plugged it in, now it is working perfectly and it is such a simple fix (Free) Apparently this is a common fault on XF and XE, The sensor gets disconnected, or packs up. 

I just wanted to share my experience, as when I was searching online for reasons Start/Stop wasn't working, I couldn't find any answers. If anyone has this problem, try this. You do need to undo the negative terminal on the battery to re connect the sensor. 

I hope this will help others with the same issue and please post if this fix works 

[Patch58]

Hi Marty where about's is the sensor in the boot mine isn't working either ? But mine has the auxiliary battery aswell so might be different 

[marty599]

Hi glyn.

The sensor is on the left battery terminal which is the big battery in the boot..........The sensor is a small plastic plug that just plugs in, I think you need to undo the terminal to get to the plug and clean it, then put it back. The start/stop started working after about 8 miles of driving, and I was elated i tell you. Hope you find it and I hope it works........If you can't find it, I will post pictures of it to help out.....I'm sure your car is the same as mine

[Richard Pomery]

BE AWARE, disconnecting your battery terminal can lead to central locking not working, as I found out after changing timing belt on my 2014 XF. Jaguar wanted £700 to fix, I purchased JLR SDD off eBay £60 & reprogrammed myself. I am told the key has to be out of range before disconnecting battery. Also  start/stop will stop working to save energy if battery falls below around 12.2v fully charged is 12.7v will start working again when voltage maintained.

[marty599]

To be honest, When my fan belt was replaced, and the battery was totally flat, the battery was taken out and charged overnight, I never had any problems with the central locking or anything else. The battery was in perfect condition and when the sensor was fixed, the mechanic I used just disconnected the left terminal on battery, plugged sensor in, It took approx 30 Seconds and now the car is working as it should.........Start/Stop working and no issues with central locking.......Also, I was stood beside the guy as he did it and the key was in my hand..........Maybe the 2015/2016 models are different from earlier models........That I don't know, as I am no Mechanic. All I know Is that it the fix worked. I just wanted to share my experience and help others...........It will be interesting to hear from others if this solves the problem from them to

[Richard Pomery]

Hi Martin, yes forgot to mention through previous searches I understand it only affects the 2014 & 15 XF models, also apparently other makes of cars as well. many reports on the net with same problem, even garages getting caught out.

On this model year as with any car of course you can use a slave battery connected when just changing main battery, to keep system alive, but not if you need complete disconnection.  I followed an youtube video on timing belt replacement, where you have to disconnect bat & remove starter to set locking pin.  After completing the job, no central locking. Contacted the youtuber & he said he forgot to mention that in his video. To late when damage done. Cost me a lot of time & stress, doing searches & finally after getting the JLR SDD software & nearly a whole day of reprogramming fixed it. There should be at least a warning on or near the battery. Sorry for the drawn out reply as although it doesn`t apply to your year, may help others with this year 2014 & 15