I have searched the web extensively and found bits of useful info but not managed to put them together into an answer to my problem. Car is Focus 1.8 TDCi 2008 with 135k miles.

Background: From a while back, occasional 'glitching' like a little jolt, while driving at steady speed for some time. On a few occasions, 'Engine malfunction' warning and power lost (limp mode?). Restarting engine in a few minutes fixed it, happy days.

On a recent longer journey, after 30 miles had first 'failure', stopped car, restarted ok, then about 20 miles later failed again, then increasingly frequent until eventually wouldn't start properly - in limp mode (1500 rpm with foot on floor) and irregular/lumpy tickover. Breakdown man diagnoses faulty injector with machine. I could hear one of the injectors making a ticking / pinking sound so accept this diagnosis. BTW the problems developed while I was running quite low on fuel, but after filling up (at JET) it seemed to get even worse, before breaking down.

Ford garage diagnosed same - one faulty injector, replaced the injector (and fuel filter), but then told me a second inject has also gone immediately. This can't be co-incidence, so what I want to know is has another injector really gone, if yes is something else causing them to break, or it hasn't really gone, and something else is causing the apparent fail. And if a 2nd one has gone, is it "their fault"?