I presume you mean the engine management light ( shaped like a side view of an engine ). It is simply letting you know that the ecu is getting a fault reading from one of the ( many ) sensors. You need to have it plugged into a computer to get the error code. You can buy a dedicated code reader from Halfords for your car for about the same price that Ford will charge you to do the check.
ok. just had mot done last week-wouldnt that have picked up a fault? Also do i need to take it to a ford garage or will any garage be ok? do you know the cost of this check? Thanx.
an MOT doesnt check diagnostic faults, it only checks the mininum requirements your car needs for it to be roadworthy ( you'd be surprised ) if your local garage has diagnostics to check your car then try them and should cost between 30 - 40 quid to check the fault then more to fix it