I have a 2016 GLE350 I've changed the battery multiple times and sometimes the fob works and sometimes it doesn't. Sometimes it will work to unlock the doors, but not to start. Other times I'll be driving and I get the dinging and red flashing key not detected warning. How can I fix this? Every site I've looked at says it's the battery, but I've changed it multiple times and tried different brands and still have the same issue.

 

What you describe is what happens when the driver leaves the car while it's running. The interior sensor knows and alerts.
​​​​​​There are several key detection sensors around the car. The outside ones allow you to unlock the car. If the interior one can't "see" your key, it'll instruct to place the key in the spot near the cupholder, in order to Start.

I'd guess that the inside sensor is defective - not knowing that the key is inside.
Defective detective.🙂

 

hi there! I'm a former MB technician. have you recently get your key fob wet? i have encountered the same problem and saw that the key fob has water marks inside near the battery terminal. another thing is that maybe the module needs to be updated.

 

In that case would it be advised to use an electronic cleaner/contact cleaner etc.?

 

You're not alone! You just have a marginal keyless controller module.
It simply needs to be repaired with a 5mn soldering job or replaced with a fresh part coded with MB Xentry.

MB insist on using 3rd party solderless modules, that are borderline defective from factory. Have a look for yourself inside module... you'll see!


Get the vehicle scanned to list what other CAN-B modules are involved with a string of failure.
When enough of these modules are soft-crashed the power Mgt module (SAM) stays awake and drains the battery flat dead: no start!

Low-voltage conditions exacerbate marginal CAN modules that are setup to run in a narrow voltage range. Outside that working range COMS are impacted with poor ability to transmit. The outcome is modules get soft-crashed until reset with a simple reboot.

Rear end modules are located furthest away from the front end network. These are the most impacted by COMS errors given noisy electrical harness.

As you begin to tackle these marginal performance issues, best engine-tranny behavior will resume. The banging 3rd gear shifts becomes seamlessly smooth. "shift adaptations" not needed!!
​​​​​​
​​​​​