Hiace AdBlue System Error

I had a similar issue with my 2018 Mercedes Sprinter. Kept getting a DEF fluid warning and the service light was on. It turned out to be a faulty sensor in the AdBlue tank, causing it to think the tank was empty when it wasn't. Could be worth checking the sensor on your Hiace's AdBlue tank. Has fuel efficiency dropped?

Thanks for the tip! I hadn't considered the sensor. How did you diagnose the sensor issue on your Sprinter? Was it throwing specific codes, or was it more of a process of elimination?

The Sprinter was throwing a code specifically related to the AdBlue level sensor, but it wasn't very descriptive. The mechanic used a more advanced diagnostic tool to see the live data from the sensor, which showed it was giving incorrect readings. I would suggest going to the workshop to read error memory and check the sensor.

Appreciate the help! Took it to my usual garage, and after testing, they confirmed it was a faulty AdBlue pump. Apparently, it wasn't sending enough fluid to the dosing unit, hence the errors. New pump fitted and all sorted for 250€!