swallows

Hi, is anyone able to point me in the right direction on this: Mondeo Tdci 2005: Very occasionally I will get a kind of double missfire and the glow plug light will start flashing and continue until ignition is switched off. This might happen once in a 300 mile journey, or twice in a 15 mile journey. No fualt codes showing at this time , and eml light off. Then yesterday had the same happen only this time eml light on and showing code P0202 (nr. 2 injector open circuit). I seem to remember that when something else is happening which isnt right, the glow plug light will flash and you will get a couple of misfires to tell you something is up, wouldn'
t deliberately introducing a misfire as a warning introduce the fault code as above? Just a thought before investigating an apparant intermittant electrical fault.
Additionally, having recently purchased this vehicle, should there not be an air mass meter between the air filter and inlet? On diagrams it appears as part of the air filter, but my air filter housing has no facilities for such. Its an ex funeral directors estate (guess, in black! no resident ghosts!) with 125k on the clock and fsh. I have recently installed a solid flywheel conversion - drives lovely!
If it does turn out to be the injector, I can see how an electrical malfunction is detected, but not a mechanical one. Is it possible to just replace the electrical bit, which I presume is just an operating solenoid?

thanks for taking the time to read this, regards, Sam