drive the car at WOT in 2nd or 3 gear and graph the pressure sensor,

if you have anything close to 4 psi at any point which is 27 kpa the exhaust is still restricted, and the car will set that code

if you used a pressure washer to clean the dpf there could still be moisture in there , if you used a cleaner there could still be some in there ETC.
will the code clear ?
have you told the car its got a new DPF fitted ?

i have cleaned doesens of thease ( factory units with a pressure washer and have had zero returns so long as you make sure there spotless inside )
if you use a pressure washer wash it out through the back side and not the cat side as the pressure washer will destroy the cat and then the filters junk.

i use the car to dry then out , i leave the DPF disconected from the rest of the exhaust and run the car at fast idle for 30 mins, when it stops steaming its dry.

Either way in my opinion your problem is the ECP filter even if you get it spotless its still a piece of crap that is likley to drive you mad.

Get a factory unit used if need be and clean that,

after market filters = wedding bells