Davery

I bought a 2012 E550 Cab a few months ago, but it only came with one key fob. I have priced out another fob through the dealer at about $450, but have not ordered it yet. Tonight I removed the battery from my fob and was able to start the car after removing the "start" button by inserting the fob and turning. How is this possible? I assumed when you inserted the powered fob into the ignition (with the "start" button removed) the car still received an electronic signal from the fob in order to start. Apparently not.

Plutoe

Dear confused, what you forgot to read was that the key batteries have nothing to do with starting the car-----amazing what you don't know!! The batteries are for all the convenience features on he car.

Davery

So when I remove my start button, I can insert any key fob into the slot and start the car? That can't be right. I can't start the car by using the start button without the key fob being near the car. I assumed this was because there was an electronic signal that verified the correct key fob.

raja777m

you don't have to insert even, just touch the keyfob without battery to the steering column or the pushstart button and press the push start.


BTW, make sure the metal key is coded to your car, usually that is 75$.
If you really want the 2nd key fob and not in a rush, wait for spring cleaning coupons and order one.

tresean1

What are you inferring, or questioning???
Now you are confusing me.

As mentioned above, your key can start the car without batteries---they batteries just control keyless entry features and Keyless Go functionality, which you apparently have installed as an option.
The infrared receiver in your key exchanges "split second dialogue" with your car's ignition, and once the "password" is verified, your car will start.
This is done because there is a slight electric signal sent from the ignition to a small capacitor/electronic bit in the key (this provides just enough charge to send a signal to the car)---thus the electronic "unlocking sound" you hear when you insert the key into the slot.
The Start button is just a piece of plastic that's used for cosmetic purposes only, because Mercedes was too lazy/cheap to make a discrete TRUE Keyless Go start button and ignition system (like all other manufacturers in the world) that's separate from cars without Keyless Go....thus they used a cover-up button that's slots into the keyhole.

You'll notice they fixed this with later models...even cars without Keyless Go locking/unlocking get a start button on the dash.

Hope this helps

kajtek1

Also shop around. I bought MB key about 3 years ago for $162 from dealer located on suburbans.
Keyless go will cost more for sure, but still lot of spread between dealers.

Davery

After a bit of research, I understand. I didn't realize the fob received power wirelessly to allow the car to be started.

Davery

I called about 10-12 dealers and $450 was the cheapest price.

cetialpha5

Try checking the dealer websites for service specials. Sometimes they offer 10% or other discounts. And then the other dealers tend to price match.

But that's not too bad a price for a keyless go key. That other quote was for some other key, I doubt it was for a W212. I remember getting a key for my Chrysler for $10 but that doesn't mean anything.