My 2012 CLS550 W218 M278 has 73K miles and a couple of weeks ago the electric radiator coolant suction fan went into "Limp" mode where it would ramp up to max high speed at a cold start and stay on for the duration the car was running. I did some research on MB world and ruled out any bad fuses or low AC r134a charge. I learned the fan relay is built into the electric coolant fan. I searched LKQ for a used one and they were priced at $497, a new one is around $900. I decided to check the coolant temp sensor but I couldnt locate it. I was told it is on the transmission end of the left side block just below the lef tside head. Theres just no room to get a hand in there, so I bit the bullet and purchased an OBDII Professional Multi System Scanner from iCarsoft model i980 for $136.00 tax and shipping. The codes I got were P050C 62 "Coolant temp implausible, the signal comparison is faulty" and P023B 00 "actuation coolant pump of charge air cooler has a short to ground" and P06DB 00 " The actuation of the oil pump has a short circuit to ground". I started to suspect a bad ECM, and brought it into the MB dealer for diagnosis, which they said was $249.00 and would be credited against any repair costs. To my utter amazement and Glee, 3 hours later MB service said They performed guided tests of the 3 faults and all actuation tests were OK, Temp sensor OK, verified in actual values fan being requested by engine control unit due to stored codes. Fan actuation is OK, clearing faults resolved the issue. Performed software update to engine control unit. The dealer said no charge for the troubleshooting, no charge for anything ! Yahoo!!!! apparently they said there was a emissions warranty recall to update the software. Sounded great to me.