4 hours ago, Vinnybhamra said:

if there was any way i could test this before going ahead

It is quite easy to test a DP sensor using a few metres of clear tubing, sized so it can be made to fit the sensor ports, a tape measure, a bit of wood, some water and a good dollop of ingenuity.

Tape the tube to a bit of wood to make a "U" at least 1.2m (4 feet) high, with one free end extending long enough to reach the DP sensor, and the other end just long enough to get hold of. Tape the tape measure down the middle of the U. Add enough water via the short end so that the level comes to about 600mm above the base of the U when it settles.

A rather poor photo of one I made earlier (years earlier) is below.

Remove both hoses from the DP sensor. Turn the ignition on, and run Forscan to monitor the DP reading. I don't think the engine needs to be running for this. Suck from the short end until the difference in water levels in the two legs of the U is about 1m (not critical), then clamp the short end tightly closed. Fit the long end to the HP port on the DP sensor. This port goes to the turbo side of the DPF, and may be marked "+" or "H". Or just guess, it will not matter. Release the clamp. The water levels may move a bit, but then settle. See if the Forscan reading has gone up. If not, remove the tube from the sensor, and repeat using the other port.

If the Forscan reading is in kPa, then mm of water difference can be converted to kPa by dividing the mm by 102. Eg 1020mm = 10kPa. (to within 1%.). This can be repeated at various levels if you wish.

If this test was done at the other end of the DP hoses (at the DPF end), then it would check for leaks in the hoses, as the water level would drop back to level rapidly if there was a leak. You would need to join the test tube to the hose leading to the sensor. It may sound a complex test, but I think it will be easier than it sounds, to do. Just needs the right tubing.

Something like: http://www.ebay.co.uk/itm/Clear-Translucent-Silicone-Tubing-FDA-Approved-Milk-Hose-Beer-Pipe-Soft-Rubber/221489619116

This tube is quite stretchy, so the ID should be smaller than the fitting it has to go over.

Like you say, replacing the DP sensor as a test is expensive. Typical garage suggestion, it is easy to do. No way would I replace it without testing properly first. I have not heard of cases where the sensor has failed. Your sensor cannot have a major failure if it is giving reasonable readings.

Alcohol (either Isopropyl Alcohol, or Meths) can be used to clean the tubes. It is compatible with just about all rubbers and plastics.

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Re Halfords Deep Clean, I am not impressed. Any term like "deep clean" fills me with suspicion, and Halfords, even more so. It only claims to remove soot. Soot is best burnt off, using one of the platinum / cerium additives and a Forscan regen. You can do that for a lot less than £85.

Ash can not be safely dissolved, or burnt, or driven through the filter media. It can only be washed out with water or some suitable solvent, back the way it came in. That means a reverse flush, with the DPF removed. Water does work. The possible problem is that it will react slowly with the ash, and any remaining ash in the DPF after washing may set harder as it dries. Thus my concern about the long term use of this. I would only do it if I was sure the DPF was clogged with ash, and I would probably do a final rinse with alcohol (eg Meths) to dry it out, then suck warm air through it with a vacuum cleaner to remove the alcohol.

Thanks for the response it does sound a bit complicated but i think i might give that a try. Currently just had the hoses off and looking at the sensor and to be honest the hoses look absolutely fine from the sensor end... I noticed that the braiding further down is torn a bit exposing the rubber underneath but the rubber also seems to be okay there. As far as i can see down the pipe there doesnt seem to be anything that could cause a major issue. Maybe the dpf itself is on its last legs? I think to be sure though i may try the test with for the sensor when i can, although as you said i havent been getting odd readings just ones that are high. Thanks for that information though :)

I don't know if you sorted out since this post is 2 years old  but in my case this message  was caused by a faulty brake pedal sensor -  the blue one. Replaced it and the annoying message gone forever. Good luck!

Had the same issue where the Engine malfunction message kept coming up and then disappearing after I turned off the car. It would pop up randomly after ignition and be gone for example the next day. There were no additional lights turned on in the dash, just this message.

Took it in to a Ford dealership and they ran a diagnosis and found that the eolys liquid was all out. The vessel was completely empty and the car could not dose the fuel (I did a complete diesel refill one day before the warning started showing up).

They filled up with eolys and the error was gone after that. It cost me about €185 for the diagnosis, liquid and labor.