why does the computor say incorrect DEF quality detected after running for a year on the same tankfull, after a couple of days  a new message appears no restarts in 459 miles, is the cars software set to ensure that annually you have to go back to a main dealer. My car is an XE Prestige auto D 180 ps Ingenium engine Nov 66 plate mileage 31890. Danny boy

There is a very good post on this over at the XE owners club! Link below! 

https://www.xeforums.co.uk/threads/incorrect-diesel-exhaust-fluid-quality-detected.9690/page-6#post-137503

I know this post maybe old but I hope someone will come across and find it helpful. I also have problems with the airbag light on my Jaguar and I did a lot of searches on this issue and came on in depth article which may be worth reading, search for "Jaguar Airbag Light On - Common Problems on YOUCANIC" This article will give you a detailed information about the airbag light and help you diagnose and fix the problem. I really recommend checking this article.

Hi Daniel.  I've just had the same problem for the second time.  It can be one of many reason but very unlikely to be poor quality Adblue.  It could be the NOX sensor, the injector or as in my case just a poor signal coming from the DEF control module that lives in the boot under the tool kit.  I would recommend taking it to a really good diagnostics place so they can get to the bottom of it.  In my case they took the controller out, put it back in and the problem went away (albeit probably temporarily).  I've attached a copy of the invoice that details what they did and how they tracked it down.

Sales Invoice SJ007643 (1).pdf

I had this problem with my 2015 XE and it turned out to be a software problem which was rectified in about 10 minutes by plugging in a Jaguar laptop and downloading a patch. Apparently this is a common problem but easily sorted.

Had the same thing come on (3) times in a 2019 Jaguar Fpace Diesel.  The sad of it, Jaguar claims they fixed it, that is was "a bolt" and within miles its on again- of course NOT under warranty this time and they want $8K to replace the def system.  According to a Jaguar dealership, Jaguar requires total replacement of the def system instead of fixing.  Of course they do....it is out of warranty!!  I would NEVER trust Jaguar again.  Regret that a 5 year old car with 80K miles on it is basically headed to the junk yard.    Supposedly the super charger is "screaming" ad was told that only "a trained ear" could hear it.  I call BS...   Obviously, Jaguar is not competent to even service their own vehicles.

Action Plan.pdf