Citan AdBlue issues and engine start problems

My 2012 Mercedes Citan diesel shows an error saying the AdBlue tank is empty, but it's full. The dashboard alert is on, there's an error stored, and the engine won't start. Could this be a defective AdBlue output from the tank to the dosing unit? I've heard the DEF fluid system can be problematic. Has anyone else experienced similar diesel exhaust issues? What's the tank capacity?

4 comment(s)

Sounds like a similar issue I had with my Citan. If the system thinks the AdBlue tank is empty, it will prevent starting. The SCR catalyst relies on that stuff. It could be a faulty sensor or, like you suspect, a problem with the AdBlue delivery. Think of it like a clogged artery in the engine's system.

Thanks for the quick reply! Was it definitely the AdBlue output in your case? Did they have to replace the whole tank, or just the pump? Any idea on repair costs?

They diagnosed it as the AdBlue delivery unit. I ended up taking it to a workshop. They replaced the unit. Cost me around 250€. It's probably best to get it checked professionally to be sure.

Appreciate the advice. Sounds like a trip to the shop is in order. Will advise when it's sorted.

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