Here is a link with some pictures of the DEF tanks.

https://www.ecstuning.com/ES254461/

https://www.ecstuning.com/Search/Sit...2146/ES254457/

Seems these stupid tanks are having a number of failures and there is an active and passive tank, each cost about the same amount, discounted around $800. Wonder it it is just one tank that has the higher failure rate?

Again, I am not an expert on these tanks but it appears they have a level sensor, a temperature sensor and a heater. These cost around $800 at a discount level and may not be so easy to access/replace.

The good news from the picture is it looks like the DEF tank is somewhat designed like a BMW gas tank with a large collar that can be unscrewed and the senors may be accessible without having to drill the tank. This assumes the collar can be removed without damage or breakage. So someone will have to be the guinea pig on this project. I would probably see if you could find a used tank for a decent price so you could open it up and come up with a solution so your car would not be apart and down while trying to come up with a solution of some sort.

Couple this with these tanks are NOT current readily available for some reason. I can only assume this is due to a high failure rate of these tanks AND/OR a possible redesign of some of the tank parts.

There is another person on the forum that the tanks are not currently available and back ordered for probably a few weeks, maybe more, for a tank from German!

There is obviously more to this situation and likely more failures to pop up in the near future.

I wonder when the letter from BMW will be coming out that is extending the warranty coverage on the DEF tanks? :D

A defective DEF system would cause the NOX emissions to probably be above acceptable values, would be interesting to see how BMW addresses this with VW Dieselgate problems.