MY 2007 E320 Bluetec, 69000 miles. Original owner. The gold coil warning sign came on intermittently and eventually the check engine light came on constantly 1 month ago. I found that the glow plug #2 was bad from reading the OBDII scanner.

I ordered all new 6 OEM glow plugs from MB and replaced them myself. Planning to keep the car for another 6 years. Kept the older 5 plugs for later use if needed.

Check engine light still stays on after 3 weeks of driving. The gold coil lights up on start up for 20 seconds in the morning and leaving work. I try to clear the CEL with the OBD scanner but it comes on the next day. The scanner reads glow plug #2 can't communicate.

The car drives fine. No hesitation, no smoke from tailpipe, mileage seems the same on 1 full tank as before.

What could I have missed?? Is there something else I need to replace?? Should I disconnect the battery to reset the CEL?? Researching the internet, is there carbon build-up in the original failed glow plugs chamber that I need to clean with a brush?? Do I need a SDS reset instead??

Thanks in advance

Pat