Good evening everyone, here is my first post on here and its a cry for help!

Basically I bought in a 57 Plate Focus 1.6Tdci super cheap with a couple of niggles, all now resolved bar this one....

I am pretty sure the issue lies with the fap system.
This is what I have: start the car from cold drives great until I hit 40kmh or if the car has been running for 4 minutes under this speed, then the engine system fault warning and red light comes on. Car goes into limp mode. No ECU fault codes. I had one for a heater plug issue which I mapped out first (maybe I shouldn't have but that can be reversed if need be). I have added 1 ltr of PATS fluid to the tank and reset with Autel. DPF has already been gutted.
What I sort of need to know is if a DPF removal file also removes the reference for want of a better term to the additive system? i have read through loads of posts but found nothing exact. Read a few posts on a couple of lines of codes that need to be changed in winols but not too much more.
I apologise if someone has posted an answer to this exact issue before in which case a link to it would be great ;-)

HARDWARE VERS: BOSCH EDC16C34/2.20
S/W 1037390500

Many thanks
John