The air filter was changed about twelve months ago, the plate is a solid plate, the EML didnt come on immediately, however, now it is on and reading a code on gas circulation low. I clear the code and it just comes back on!
My main issue is with this starting thing. What is a VNT?
Twelve months is a long time if you are doing a high milage or if you are in a dusty enviroment (or the salt in the winter) i change mine every 6months /6k whichever comes soonest - Ford recommends very long service intervals - this trouble with a paper filter (stock Ford or pattern) is it filfers well but it becomes clogged quite quickly because the tiny holes get plugged by dust - a pattern one costs about £6, and it takes a screwdriver and 2 minites to change - the engine should run better with a fresh air filter, pull better from low revs (especially before the turbo "kicks in") and you should see a (slightly?) better MPG and (Hopefully) a bit less smoke on startup because a fresh filter tends to lean off the air/ fuel mixture before the turbo boosts up
These cars respond well to regular (frequent!) servicing, if you try and stretch out the service intervals it can cost you more in the long run - a stitch in time..... Ford's recommended intervals can be ridiculously long
Your EML is liable to come on as you described, sooner or later, this is normal for a Euro4 Mondeo, after reset the EML may come on straight away, or it may be days or weeks, 10s or hundreds of miles, - some prefer to run with a solid plate and let the light come on, to running with an unblocked EGR
VNT stands for Variable Nozzle Turbo aka variable vane, on the exhaust side of the turbo, in the exhaust manifold, there are vanes that direct the exhaust gasses onto the turbine, this improves the response/ reduces lag at low revs, and controls maximum boost at high revs (without a wastegate required) these vanes are controlled by the actuator via a rod, they have a tendency to get coked up over time, eventually, the vanes can sieze and damage the actuator