glow plug warning light woes

Driving a 10-reg Greenline.

Was driving down M40 couple fo weeks ago (constant 2200ish revs in cruise control) and glowplug light starting flashing, but with no loss of engine performance. Went straight to dealer, by which time the "contro system for exhaust" had also come on, and then gone off again. Glowplug light was still flashing when restarting to show the service engineer, but they couldn't fit me in that day do booked car in a couple of days later. Glowplug light stopped flashing when I restarted to leave the dealer's.

2-3 days later, on way to dealer's (again on M40), Glowplug started flashing, gave warning, then stopped, immediately started again with new warning, stopped, and kept doing this for 10 minutes. Again, no loss of performance that I could detect.

Dealer checked diagnostocs, and there were no errors recorded at all, and they found no obvious faults.

Now today, light started flashing again on way home and didn't stop for 30mins. During that time, the alternator warning light came on a few times and went off again. Restarted car at home, and no warning lights...

Help!

Edited 5 March, 201412 yr by mb1rgw