Where do I top up my Peugeot 407 HDI's emissions particle filter fluid?

I have a Peugeot 407 HDI. A warning signal comes up saying I need to top up my emissions particle filter fluid. Can anyone tell me if I can do this myself and, if so, where it is located?
It's in a tank under the back seat. But this is a dealer job.
Answered by Honest John on

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