My DPF light as come on 3 times in the last 4 weeks, the first two times it just went off but it as just come on again and doesn’t seem to be going off. 

Have you been doing lots of short journeys? 

Is the engine running rough or is it in limp mode? 

The first step is to run it on the motorway @ a steady 60/70 for 20 - 30 minutes.

That will force a dpf regen /clean. 

Hi go buy a tin of aggressive DPF cleaner, stick it in the tank and go give it a run as Shytot suggested, Euros do a good one in an orange and black tin I have used that a couple of times and it works.

Steve.