Stopped at a restaurant last Thursday while on vacation in Prescott AZ. When I finished, my 6 month old (to me) 2012 E350 CPO with 20K miles would not start, in fact nothing worked. Called AAA to check the battery and it was fine. They towed it to a local garage specializing in German cars. They check the obvious things (battery, fuse, immobilizer, etc) in about 15 minutes and said they had no clue. Called MB roadside assistance and after being on hold 20 minutes, they said they would arrange a tow to the nearest dealer in Phoenix, 100 miles and 2 hours away. I rented a car in Prescott to continue the vacation. Got a call from the dealer Friday afternoon saying that they could not complete their diagnostic procedure because the procedure REQUIRES USING BOTH IGNITION KEYS! Since my spare key was home in Vegas, I am now waiting for the dealership to get a key from MB, maybe Monday.


Meanwhile, I am eligible for MB trip interruption protection due to the breakdown being more than 100 miles from home. However, they only reimburse you for expenses for three days and today, Sunday, was my third day. So I have to pay for the rest of the rental until the car is fixed, which is likely to be a week. The service advisor is almost certain it is the starter. Apparently this is a very common failure on the E and S series. However, they can not order the replacement part until the diagnostic procedure PROVES that the starter is the problem. So maybe they complete the procedure on Monday and then maybe they fix it by Thursday if the part gets there in a timely manner.


Trip interruption pays up to $300 a day but since I was on vacation, the only added expense is the rental (about $300 for the week) but that makes no difference to MB. I'm going to have to eat it. The only good news is that the dealership has gone above and beyond and promised to bring my car to me in Prescott after it is fixed, so I won't have to find some stranger to go with me to Phoenix to get the car.


So from now on I am going to carry my spare key locked in the trunk tucked around the spare tire.

 

OUCH! Seems to me like you may have a case to get some additional "assistance" from MB. I believe that the 3 days limit exists because most dealers will give a loaner while they are fixing things. I recommend calling MBUSA to see if they can help you out - perhaps by sending you out a loaner so you can ditch the rental.

If you have Keyless Go you might have an issue with this plan.

 

I was thinking the same thing from what I have read about key battery issues. Unbelievable that they need both keys to run a diagnostic!

 

That stinks, but sounds like MB is doing what they can. Good luck!

 

They must suspect a key identity problem as well as the starter. Bummer.
Putting a key in the trunk usually ends up with the trunk popping back up in your face or a warning that the car cannot lock due to a key present. Best to keep the spare on you at all times. I always bring an extra key when I travel any distance from home, whether on vacation or business, after locking myself out of other cars on more than one occasion...

 

Yeah, the dealer says there is a slight chance of key identity which is very rare but they MUST rule it out before they are allowed to order the starter.


Did not know about the inability to lock. Seems stupid carrying 2 keys in my pocket.


I called MBUSA about the rental since I did not get a loaner and they immediately passed the buck back to my dealer. Also, my local LV dealer handles the rental claim, not the Phoenix dealer repairing the car. The Phoenix dealer says they called MBUSA about possibly pre-authorizing more of the rental covered and they said "no".

 

Take the battery out of the key and the trunk will not pop open.


Also, if you have the other key on you outside the car it will lock doors and trunk with the key in the car with battery in it.

 

Interesting. I learned something new. I thought you could not leave a spare key in the car and lock it. If you lost the key you were carrying, how would you get to the spare key in the trunk?

 

If you have MBrace subscription, you could either call MB or unlock it with the SmartPhone app .

 

The replacement key was delivered to the dealer today and the car started immediately. They gave no ideas on why the key broke. Again, I will never go out of town again without both keys.

Now I'll go to my local MB dealer to file my "trip interruption" claim to see if they will pay for all of the car rental instead of only 3 days.

 

This does not quite add up.
Does your car have keyless-go?

 

Keys on most, if not all, cars made in recent years have an imbedded microchip. If the ignition does not read the correct chip ID - no start. Long gone are the days when the mechanical configuration of the key was the only thing needed for the engine to turn over. No clue on why my microchip failed.

 

That was only if you had keyless go. The car would detect the key inside and when you lift the handle, it would unlock. As you don't have keyless go, you can lock the key in the car. Even if you had keyless go, you'd just have to put the key in something like an antistatic bag or a metal container to block the rf signal and if the car can't detect it, you will be able to lock the doors.

 

Great, that is what I will do. The opener portion of the keyfob still worked, not the ignition, so I can open the trunk and get the spare. Of course that won't help me if I somehow lock my key inside the car.

I'm just stunned that any MB dealership would not carry spare keys in their inventory and/or have the ability to re-program a key.

 

My 2010 Smartkey (NOT keyless Go), has a mechanical key made into the end. When I picked up the car, it's one of first things the sales rep. showed to me. It's also in the Operator's Manual.
Designed so you can operate the car even if key battery fails. Don't know if it would have worked in your situation though.

 

The mechanical key just allows you to open the door, correct? How would operate the car with it? Everything is Radio

 

This is with the Smartkey that is inserted into a "hole" in the dash. You just insert the mechanical key instead.
On my key, there is a small slide at top and next to it is a longer piece with a hole at the end. You push slide back and pull up the other side and voila, there's a key!

 

The mechanical key is only to lock/unlock driver's door, trunk and the glove box.


To start the car the key fob is the key but if there is an issue with car not recognizing the key then no start.

 

I don't think a Keyless-GO car will unlock if there is a key inside and you pull the door handle without the other key on you outside the car.

 

Say wha? The mechanical key has been a part of the Smartkey system for over a decade. You cannot start the car with it. Was your sales guy having fun with you or what? You actually saw him insert it into your starter switch?
Even Keyless Go cars have the same "hole" in the dash. You just pop off the button with your fingers and use the "hole" to insert the "whole" key.

 

I stand corrected. Just checked OM and it does not start the car. Pretty sure the sales rep told me it did, but that was almost six years ago.
Batteries in both Smartkeys are approaching six years old, so guess I need to change them. Actually one key is only used when go to dealership annually as it has no other keys on the key ring. Only care one key when I go anywhere.
My Nissan Rogue has a procedure with "keyless go" that if battery dies, you hold the fob against the Start button and it will work.
Does seem strange that MB would develop a system where you can't start car if battery dies. Of course, you can open car, get out OM, find battery number and hike to nearest drug or grocery store and purchase a new battery.

 

It's a Mercedes thing, makes it really hard to steal their cars. Not really stolen too often. Been like that for a while. How much was the replacement key? They're not cheap like other manufacturers.

As for starting the car with dead batteries in the fob, I believe you can still do it, you just put the key in the dash. On mine if you just hit the button without it detecting the key, it just says key not detected. Usually it's because I hop in real quick and push the button before I'm fully seated, only happened once or twice, then I take the key out, and then a second or so later it sees the key.

Also I'll have to read the manual again, I think there's some different logic if it notices two keys vs one key as to whether it will lock or not with keyless go.

 

This might have been answered elsewhere but I cannot locate it. With keyless go, if the key FOB with no (or dead) battery can start the car by inserting into ignition slot, does it require some type of communication with the car to start it and, if so, how is that accomplished?

 

Noticed yesterday that I can get two fob batteries at grocery store for $4.

 

I just saved 15% on my car insurance with Geico.