preglow plug time relay or glowplug
 

I have a 96 E300 with about 101000 miles on it. The glow plug indicator does not turn on at start up but it stays on after it starts. The OBD code is P0380 which points out to faulty relay or glowplug. Does anyone know how I can test which of the two is bad? It continues to start, will one bad glow plug cause it not to start? Help pls

You probably have a bad GP. It will start with one or two bad GP's if compression, starter and battery are all working optimally although may run rough initially.

Go to dieselgiant.com and follow the turorial there for testing GP's for the W123. Different engine but same pricipals.

Search here for "606 + broken + siezed + GP" BEFORE attempting repair.