[ours2012]

what engine is in the Van

 

[ours2012]

Yours must have a DPF fitted then
Find the dpf, follow the rubber hoses up the exhaust system you should see it

 

[ours2012]

So you can see the sensor at the back of the engine?
Looking at the picture of

the sensor 1 part must go to the DPF, from the metal part with the blue bung on it to a rubber pipe
If you have located the sensor , can you get at it from underneath if you drive the van up a kerb
Or on Axle stands/ramps

You have checked the rubber pipes going to the dpf?
If 1 is split, you will get this error