Since never owning a diesel with a DPF on , I would have expected the engine management light to come on , like one post say's , give it a good blast for 20 plus minutes , either motorway or just in a lower gear , the idea is to get it hot enough to burn off the particles , but it may have also run out of the fluid that gets added to the fuel , i think a tank lasts about 40K.
On most diesels , it means that one of your heater/glow plugs is faulty , if so , you need to change all of them and not just the one . Being summer and warmer , the engine will start ok , but when it gets colder you will find starting harder and usually will get a cloud of smoke on start up !
If you have a meter , follow the leads back , normally to a large relay box , if you can open it and gain access to the plug connector, unplug it and measure the resistance of each , one lead to earth and one at a time to the pins going to the glowplug , they should all be the same or very close. On some older engines it is just one lead feeds them all , so this method is no good , you would have to take the lead of all and test them directly.
As I said before , If it is a faulty plug , you have to change them all , otherwise you will start to have prob's with the others shortly afterwards , thats why they are normally sold in sets.
If it is a plug and you are going to replace them yourself , the tank of fuel before use plenty of diesel cleaner in and give it a good blast as said earlier . Also , soak the threads in WD or something simular the night before , as they can be a pain to remove , they can break-off and drop into cylinder , then normally its a head off job !!
If it is the DPF , you may have noticed higher fuel consumption recently , normally a sign that is the prob. If keeping the car , some can be removed and the ECU remapped. Will still pass MOT no prob's and you will notice the engine run better too.
