The light comes on (usually) when there's enough of a pressure differential between the sensors before and after the filter. This actually equates to a voltage difference in the return values from the two pressure sensors. If one of the sensors becomes faulty, or its electrical connection becomes intermittent (or fails) then the ECU has no choice but to assume the filter needs cleaning. Naturally, with no filter actually there, a regen will be requested (and the necessary fuel sent in the exhaust strokes) but the apparent pressure will remain unchanged - so the ECU will assume that the DPF cannot be cleaned and bring the DPF light on.
You could try cleaning the MAFS, but I'm not sure it would make a difference. Use electrical contact cleaner, do NOT put anything in the opening, let it dry before reinstalling it. A faulty MAFS usually results in the wrong fuel mix and boost levels, resulting in poor performance but usually no warning light until the MAFS fails, and then it's the normal Check Engine Light that comes on.
