Apologies up front for this long shaggy dog story but if you are interested or have such problems read on.
About 4 months ago my 2016 3.0 jag started to have a random intermittent fault which has followed no particular pattern. The main screen goes off and then the vent system shuts down. This will then come back on in part or all of it after a varying period of time. This could then keep happening every few minutes or not for an hour or so. Sometimes it may not happen at all.. The software has been updated. Following a protracted process to get Jaguar involved (no warranty) I just wanted them to search their dealer ships if a similar problem had been experienced elsewhere.Jaguar finally got involved. They took the car in and witnessed the fault. They stripped the car almost bare having thought they had found the problem but did not. Eventually after 2 weeks they said it was the alternator and duly changed this. They then said all was well, they had tested the car so come pick it up. I did that drove it a mile down the road and it went into fault so drove it straight back and showed them. They had the car a further 2 weeks but as the car was not in fault they said it was probably ok and come pick it up. I did and again a few miles down the road it went into fault again and has faulted many 10s of times over the last 5 days. They had run the car for approx 50 miles whilst they had it. They now tell me there is nothing they can do, their technical people have advised, unless the car faults and remains in fault. So I am left with a car which has continually randomly faulted for the last 4 months which i will have to drive until it remains in fault - which it may never do.
It beggars belief in todays age that the main dealer with support from the central technical staff have admitted they do not know what to do to find the fault and have handed it back as such
In fairness to them the engineer working on the car had it all stripped out checking all connectors etc check the battery which I am suspicious of as it is 4 years old but gives 12.7v engine not running and 14.4v running. I also appreciate find a fault when it is not present cannot be easy.
This is my very first and possibly my last Jaguar. I have always been skeptical about their reliability but liked the shape and sound of the f type so much and read mostly positive reviews thought I would give it a go.
Think I will stick to my Nissans in future ( not that I can sell the jag with this fault)

 

Install a new battery, and call us in the morning?

Battery/low voltage issues cause SOOOO much weird stuff with these cars.

Is the 12.7V after an overnight rest, or just after running?

 

The very fact that the dealer suspected the alternator lends support to the suggestion of replacing the ageing battery with a new, FULLY CHARGED battery. As Carbfuff2 has correctly stated, inconsistent and low battery voltage does cause random and sometimes difficult-to-trace faults. Start with a new battery...and reports of unreliability are vastly overblown (and I say this having owned many Jaguars).

 

I'm with Carbuff2 - first thing I'd do is change (or at least fully charge) the battery before spending money on diagnosis.

How long had you been using the car before this issue arose? That's how to determine reliability. Was the car used a lot, and the battery kept topped up. or was the car left to stand for days at a time? As noted above, these cars, like most modern vehicles, place high demands on the electrical system and if the battery goes low through age or low use random "faults" can manifest themselves.

 

Thanks very much chaps for the quick responses. I bought the car in December last year with 8.6k mikes. It has now done 11k. I don’t use it much and as you can see it has not been used much before I bought it. It will generally stand for a week or two then I will use it for a day or two. Never a problem starting.
I have been regularly checking the voltage as the battery from previous reading forums was my suspicion. Generally after letting it rest for a while it varies between 12.4 and 12.7.
hapoy to put a new battery on but jag tell me system needs a reset . I have read elsewhere that if you don’t reset the system will do this itself eventually so I don’t need to take it to jag. Reluctant to take it to jag as I can get and fit a new battery myself for half the cost. Any knowledge on this one?

 

1). In light of the use history you give, the battery is definitely the first suspect.
2) The act of disconnecting the existing battery and installing a new (please, FULLY charged) battery in itself effects the "reset". No need to do anything else. (But you will likely have to reset the windows, clock, etc. All of this is in your owner's manual).
3) Contrary to what one might think, dealers very often neglect the battery as the prime suspect - and yours might just be such a case. But your low-use battery is due for replacement anyway, given its age. If the new battery solves the problem you are having, you might consider purchasing and installing a CTEK battery maintainer to eliminate this sort of issue in the future.

 

Thanks again for the info. Not having to have jag reset is all I needed will sort out a new battery over the weekend and will update the forum with the result. As you say it is nearing its sell by date but jag insisted it is ok. If nothing else it will eliminate battery and alternator from the problem and if it solves it smiles and thanks all round

 

Make sure to top off the new battery before installing. Most new batteries are not fully charged when they are shipped and often sit on the shelf for months before being sold.
Best of luck.

 

Resting voltage of a fully-charged AGM battery should be in the 12.8-12.9. It could be just old enough that it's on the border and causing sporadic gremlins. Bite the bullet and replace.

 

Also.. I had a bad experience once!! bonus for movie reference ha.
but I had a CTS started acting crazy, needed to jump it off a few times.. I bought a brand new Yellow top optima 300+ battery for it.. soon issues were worse.
short of the long story, my new battery was also bad.. Optima replaced it for me.. zero issues on after that.

 

I have now fitted a new battery and two journeys today without a problem. Fingers crossed and everything else. Will give it a few weeks and if this has solved the problem will go back and talk to local jag dealer who said it was not the battery but won’t count my chickens just yet. Again thanks to you all who have replied your comments have been most helpful.

 

It’s that cool wrap you have, pulling all the energy from the battery,
Fingers crossed for you, hopefully one and done.

 

Don’t waste your effort with the dealer. They’ll just politely listen to you and immediately forget what you told them.

 

I am dealing with this exact situation currently with my 2017 f type r - I swapped out the rear battery and put a new lithium one in and I’m still having the same issue. When I was uploading the new transmission tune from VAP the battery died. Took me 4 days to get the car to start and upload the file at the same time. About 2 weeks later this starting happening and has been going on for 2 months. The car is scheduled to see dealer this upcoming week. Should I be replacing the front battery too? CTEK charger/maintainer for rear needed? It’s too hot in Texas to not have A/C right now

 

Front battery? There is no front battery. You have classic symptoms of low battery voltage. Please note that your new battery "died" while you were installing the VAP program...and please read the entire thread - you will read that the perplexing symptoms in the OP's car were cured by installing a new and fully charged battery. And yes, a CTEK unit used consistently, definitely.
the mantra is "battery, battery, battery..."

 

I think some early, two battery models had their second battery in the front. It surprised me when I learned that.

 

Hi
as the other chap said mine had no front battery. Since changing my battery the fault has been cured but as I don’t use the car much I have done some experiments. If I leave the car for 4-6 weeks not using it I can get the same problem (no cetex trickle charge) . I then fully charge the battery and all is fine. So it is a battery problem and unless the battery is fully charged the problem is likely to emerge.
I did not buy a jag battery, they wanted £350 but bought a similar battery (same power etc) through Tanya for £140. So whether the jag battery has some special kyriptonite or something in it, they need trickle charging if the car is not used regularly
good kuck

 

Never heard of that before and I very much doubt any F-Type ever had a front battery.
Mine is one of the earlier coupes, built Oct 2014, and it had both batteries in the rear.

 

One comment: Ctek is a must. Install one and connect the pigtails for optimal battery performance. I connected my pigtails to the bus bar and negative post in trunk. My SOP is to connect the Ctek when I park my car in the garage. It takes all of 1 minute, small price for battery maintenance, the wires stick out of trunk when closed with no issues. I cannot stress enough times CTEK IS A MUST. IMHO
Frank

 

@sov211 i think you’re misunderstanding what I said. I clearly understand what this post was about. I have put in a NEW antigravity battery in the car a few weeks back. I was having this issue before the new battery. I put the new battery in and I’m still having the same issue. Please disregard the front battery question. Maybe it’s an alternator problem? The gentleman that made this post had his alternator changed and then put in a new battery in. His car now works. I have put in a NEW battery and car is still acting up.

@frank barone thanks for the advice. I’ll be sure to grab one today.