I guess the filter warning sensor is just a pressure switch so maybe a split fuel line set it off and peed on the exhaust manifold - pure speculation though.
The engine itself appears everywhere, it's a 1.6 Diesel, used in the small Peugeot's, Citroen's and others.
I know petrol would catch alight in this way, but would diesel?
I guess if the exhaust was hot enough...?
(Just thinking out loud!)
Petrol or desiel will not catch fire if dripped onto a manifold, there is not a real ignition source, it simply vapourises, it does not ignite.
Most likly an elextrical fault maybe made worse by a fuel leak.
Just want to correct you there mate, not sure about diesel as its ard to ignite but petrol certainly does catch fire whenit touches a hot manifold. Before i had chance to put the overflow pipe on the carb (its there for a reason....) i wanted to see if it would start, got it running fo half an hour and it suddenly spluttered, fuel out the overflow onto the manifold and hey presto a lil fire. It was nothing big and no damage was done but it certainly will ignite on the manifold!