First encounter on my 2000 Benz S500. Car will only start after I reset my ECU using my MB Icarsoft. Initially, a dtc code reads "ECU communication failure with your vehicle" hence, I have no recourse but to erase the code and the car will start right away and everything becomes normal. Typical symptom like this, one would normally suspect battery, alternator or starter but it seems it's none of these and it's simply because when I erased the code or reset the ECU, the car will start fine and all systems are working. But once your turn it off and leave it for an hour or so - especially the following day - starting the car will only give a quiet click and lights on the instrument cluster and not even a "clicking" or cranking sound. So far, that has been my routine: get my Icarsoft obd handy and the car is ok. Checked all the fuses and relays but it seems everything is fine. My mechanic told me that the ECU or ECM could be the culprit. Am now thinking of removing my ECU board on the passenger side and send it to a computer exchange company to have it repaired or reprogrammed. But before doing that, any thoughts or ideas are of course most welcome.