Got a saab in that has just had an egr valve fitted to cure the code p0400 which it has done. On road test the car started off much better than before until about 3 miles in it went into limp home mode/reduced performance and it popped up p242f unkown fault. The p242f from googling is DPF sensor range performance?

I checked the dpf saturation in actual values and thats at 4%, the particulate difference pressure is 2kpa when idling. I think this all looks normal but i havent had much experiance with dpfs. Any tips on where to go from here? (apart from to the dealer!haha)
Thanks

P.s Just done some digging on this forum and perhaps the dpf is blocked due to a stuck egr valve? But i dont understand why the car runs fine until its done about 3 miles or so.