On my journeys tonight through the back roads in Barnsley I was unfortunate enough to have to pass through a couple of 8-9 inch deep pools of trapped water.. I passed through them slowly, however 20 minutes later the dpf warning light is on and the engine idle is very lumpy. Any ideas? Fyi...My car according to the previous owner has had the dpf by-pass pipe fitted internally. I'm guessing its water damage but not sure why whey the dpf is fairly out the way from the ground.