Originally Posted by GVK.

Obviously could be either or both causing fault.

On the modern Fords, if the glow-plugs fail it causes engine to go into limp mode.

Have seen it a few times recently on Fusion/Fiesta TDCI, Focus/C-Max TDCI.

If it's a glo-plug circuit failure code coming up, I remove and bench-test the glo-plugs and replace as required.