W202 ECU Light on starting

[jonsey1994]

I have a 1998 W202 2.2D non-turbo estate auto with 185,000 miles. On starting normally on the glow plugs, the ecu light remains on and after a few moments the engine becomes lumpy and the transmission is in limp mode. However, if you start it on the glow plugs normally, let it run for few moments, turn it off and then re-start immediately without using the glow plugs the ecu light goes out and she runs fine. Does anyone have any ideas as to where the fault lies? I have had it on a diagnostic but the fault is not identifiable.

Thanks!