Cam sensor is most likely, but there are a few other things it can be - crank sensor, accelerator pedal, high pressure fuel pump, injector, etc.

Who checked them and told you they are ok? If a Ford Main Dealer, then I wouldn't attach any more importance to that than an assurance from the family cat.

One of the difficulties is that they don't always retain the fault codes, sometimes they clear them for no apparent reason. The flashing glowplug light indicates a fault code has been written, but doesn't necessarily mean it will still be there when checked with a code reader later on.

How / when does it come back to life? If it runs agains once allowed to cool, this indicates cam sensor - because when they are duff they become sensitive to heat. It is a hall-effect sensor and contains a semiconductor, the output voltage of which is sensitive to heat - so when the sensor is duff and is producing a voltage which is barely readable by the ECU, a bit of heat can push this voltage into unreadable territory.

Hope that helps. Cam sensor is 24 quid from dealer, so it's worth trying. You can fit it yourself in 2 minutes with only a 10mm socket and an 8mm socket. Please don't pay a garage to do it, this will make a little bit of my soul die. If you want a detailed walk-through then let me know and I'll post one.

Edited by gfewster on 15/12/2010 at 23:01

How long have you had it? If less than six months then reject it under the sale of goods act. Post something on the Legal Matters forum and you'll get better advice on this.

Negotiate better with the garage. Tell them no fix = no payment. What does the garage say about the warranty? Tell them to just fix the damn car and then contact the warranty company for payment.... they sold you the warranty!

Another damning indictment of aftermarket warranties. They might cover replacing failed parts, but they don't cover diagnostics costs - and half the expense these days is diagnostics, because cars are so complex and dealers' "fitters" are so unskilled.

Ive been called to advising they have found the problem im told the diesel froze and there was a airlock in the fuel system and this caused the engine to stall, theyve sorted it im told and also replaced the battery as it was damaged from being started whilst they had it, they dont know why the glowplug light came on though, So i will find out tomorrow if they have solved the problem.

Does this sound genuine?