2011 ML350 Bluetec. Car is running great, but has CEL on. OBII scanner shows one code, U0106. Tried clearing it, but on the next restart, CEL is back on. I replaced the Glow Plug Control Unit Module, reset code, but again on next restart CEL is on and the U0106 code is back. I pulled the plug off the Glow Plug Unit and using an Ohm meter checked the reading for the glow plugs and all appear to be fine. The car starts and runs fantastic. Any ideas on what to check?