MPG I've LOST 10 MPG needle drops like a strippers knickers

[GavMc P11GT]

I have normally always been able to get around 33 to 35 miles per gallon in my remapped 102 T6 we recently travelled fully loaded from the North East down to Norfolk and back and up until the last 20 mile of the journey it was without problem. However, the last 20 mile saw us getting engine management light on the faults listed were Lambard sensor active also fuel pressure sensor active. The fuel economy went from fully loaded and doing approximately an80mph an hour all day. Achieving minimum 33 mpg to now struggling to get 26 mpg on cruise control at 70 the faults were cleared on vcds and so far have never resurfaced but the fuel economy is dire. I have just put 40 quid in done 19.2 mile empty on the motorway using cruise best I got 27 mpg the needle on the fuel gauge has moved by approximately a quarter tank.
I cannot see any sign of a fuel leak nor can I smell any diesel the only thing I suspect is when the engine is cold There is a small injector knock on pot 4 it seems to go away when warmed up.

Any ideas where to start with the money pit?

 

[Garyde]

Is it regen'ing frequently?

I've noticed my fuel consumption drop massively recently, but I've got an issue with it regen'ing too often which is the cause of the consumption issues.

 

[GavMc P11GT]

No nothing more than normal. I’ve just tested fuel rail pressure by following this video and when I check with the engine off it would seem there’s no pressure at the fuel rail now I’d expect with no pressure at the rail with the engine off it wouldn’t start but starts no bother at all.

Have checked injection deviation and they are all perfect but it’s just used qtr of a tank of derv to do 50 mile

 

[mmi]

The video is about petrol engines.

T6 diesel measurements below

Start up fault

Hi again, I'm trying to record my van when in fault with my new VCDS. I think the attached might show the fault? The problem is the fault doesn't present every start up. Once when I was trying to record it the VCDS just displayed n/a in every column. I've ticked the boxes that delmassive...

www.t6forum.com

Have checked injection deviation and they are all perfect

How much is perfect?

 

[GavMc P11GT]

No nothing more than normal. I’ve just tested fuel rail pressure by following this video and when I check with the engine off it would seem there’s no pressure at the fuel rail now I’d expect with no pressure at the rail with the engine off it wouldn’t start but starts no bother at all.

Have checked injection deviation and they are all perfect but it’s just used qtr of a tank of derv to do 50 mile

My bad I copied the link from the next video to the one I had intended to reference