2007 DAF LF 45 Dilema

Hi Guys

I hoping you may be able to give me some advice etc. I own a car dealership and have recently purchased a DAF LF45 7.5t Horsebox (no taking the p…!) for the wife and kids etc. I have had it 4 weeks and its been fine however the dreaded engine warning light came on along with exhaust Gas light and reduced power by i guess 20-30%. A truck chap looked at it yesterday and reported the fault “after treatment outlet NOX” he said it needs to get up to 240 deg to clear… but ideally needs to be loaded as adblue only gets added under load/hot. A friend who is a fleet manager has cast doubt on this saying it has no DPF and is a constant system, weight and temp should be unrelated…

Box weighs 5.5t without a horse so up to a reasonable weight as it stands, the light came on after motorway journey with a horse in the back so about 6t. i took it for a 30 mile drive and no joy.

I have noticed that the adblue pump has recently beed changed also the adblue is full and I’ve done 300 miles it it doesn’t appear to have moved. The truck has only done 1000/2000 miles in last 2 years since proper coach built conversion so i think a blockage somewhere? any tips etc would be grateful as people have spoken about very small filter and the like.

Moving forward I’m happy to try to fix however am mindful that my wife will only do about 4-5000 miles a year used 3 times a week so this may be a recurring issue… …again any advice etc would be most appreciated.

FYi, Im sick of cars but loving the truck (boys toys etc)