Can anyone help my brother in law has a 2003 TD4 which is prone to over run once the ignition is switched off if it is cold or wet. This happens on long or short journeys, and now thw SRS light is constantly on.

Hi All Can someone please help, my brother in law has a 2003 Freelander TD4 which he loves but when it is cold or wet the engine over runs when ign switched off, this happens even after long runs. Vehicle has been to a Dealer and stopped doing it for 2 days but now problem is back, also the...