I have a Ford Focus Titanium & in December I noticed that the immobiliser light ie the one above the general warning light, occasionally flickers on & off, this is the light which flashes every few seconds when the ignition is switched off.

The above only occurs intermittently & I cannot find any particular pattern to this. I have had a word with my local independent garage, who have a range of computer diagnostics for my vehicle & at first they thought this would identify the problem but after having a word with a Ford expert they are not so sure.

I have changed the batteries in both keys fobs & used the different fobs separately thus eliminating this problem.

I have been on several Ford Forums & it would seem that the cure for this problem, which seems to occur on some Ford models, is somewhat hit and miss. There also seems a wide range of problems which could happen if the fault is not fixed, ranging from a total shutdown of the car or just living with the problem as I have already driven over 300 miles since I first noticed it.

I wonder if anyone could offer any advice?

have you had the battery checked? if your battery is on its way out it might cause a problem im not 100% sure but its worth looking at (process of elimination)