I had a dash message to check the key fob battery. While returning from an airport trip, while on the highway the car simply quit running. the steering wheel went up to the highest point and the car turned its self off. I had started it originally with the start button. I pulled over, off the road and no power steering or brakes either. Then I thought let's try using the key to start the car by putting it in the switch in the dash and it did. Ran perfectly the rest of the way home. Is it possible the bad battery in the key fob could turn the car off while driving?

 

Good Day,

Honestly I don't think that is possible, the key fob battery system works differently and doesn't affect the car while in motion..Maybe you do a general check!

 

Car would have thought key was not with the vehicle, but that should not shut down the car, for safety reasons (though Mercedes were early adopters of keyless systems)

The reason the key works in the ignition lock, is the power is self induced by a coil in the lock. The fob will work without a battery there.

 

I do not know the answer, but i would replace the key fob battery and check.

It does make sense the car would stop working if the key fob battery went dead and the car was originally started without the key in the ignition.

 

It sounds like you experienced a sudden loss of power, which can be quite alarming. While a low battery in the key fob usually affects the ability to start the car rather than causing it to shut down while driving, there are other potential causes for this issue. One possibility is a malfunction in the Electronic Ignition Switch (EIS) or a fault in the Electronic Steering Lock (ESL), both of which can lead to the symptoms you described. Additionally, a failing ignition control module or a faulty crankshaft position sensor could cause the engine to shut off unexpectedly. Electrical issues, such as a loose connection or a failing alternator, might also be at play. It's crucial to investigate these components to ensure they are functioning correctly. To diagnose the problem accurately, I recommend reading fault codes from the EIS and ESL modules, as these systems are directly related to the ignition and steering lock functions. If you're doing this yourself, a full system scanner like the youcanic scanner would be ideal, as it can access all vehicle systems. However, if you only have a basic OBD2 scanner like the Autel AutoLink AL319, keep in mind that it might only read engine-related codes and not provide a complete picture. It's often best to consult a mechanic if you're unfamiliar with these systems. Have you checked the alternator and battery connections to rule out any electrical issues?