I am at my wits end on this issue. 2011 E350 4matic sedan with keyless go. Everything works great with the keyless go most of the time but about every 10th time I exit the vehicle, the remote stops working. No door locks, not remote start nothing. New batteries in both remotes and the red light flashes on both. If I manually restart the car, all issues go away until the next time. The dealer has inspected the car twice now and no problems or codes detected. The problem does not seem to be related to where I am in relation to the car so I don't think it is an antenna problem. Happens on both remotes. This vehicle has never been in high water or damaged in an accident. I am not really excited about the newer E cars and would like to hang on to this one a little longer. Please please please someone give me some direction on this.

 

Does the car detect both Keys when Keyless Go issue happens ?

 

Attached bulletins may apply.

 

It is interesting that if the keyless go stops working, the second key will work. It does it on both keys whichever one is in use at the time, the second will work.

 

When these problems occur are both keys in the car or at the car?

 

It doesn't matter. It does it when both keys are in the car and also when only one is present. I've noticed that when the problem occurs, the link to the operating key fob is lost when the car is turned off. The dash display says that key is not present. I have ordered a replacement keyless go module to see if that could be the problem.

 

check the voltage on you new batteries in the fobs. Ensure they are 3.25V showing. if it 3.11volts or less. that is the problem. Also make sure you assesory battery in the trunk is up to the job as well.

 

I checked the voltage on new batteries in both remotes and you are absolutely correct. Both new batteries were 3.01 volts. I have installed new batteries of a different brand and they are reading 3.25 volts each. We will try these for a while and see what the results are. Thank you for your help.