It's been a while since I've posted here (and never in the X166 forum). We purchased a 2017 GLS450 for my wife in March from a Chevy dealer of all places and it only came with one key. I have owned enough Mercedes to know that you should always have two keys given the pain and expense of having to deal with a "bricked" vehicle should you lose your smart key and have no backup, but I'd never personally had that happen to me. Suffice it to say, that exact scenario happened to us about two months in to owning our GLS.

Symptoms were initially intermittent functionality of Keyless Go to lock/unlock the vehicle doors. That progressed to the Keyless Go start button for the ignition going inoperative (within only a day or so of the prior symptom) via the "Key Not Detected" warning on the dash, but we could still start the car in the key slot with the smart key fob. That then progressed within only 24 hours with the key no longer being detected or recognized by the car whatsoever.

After troubleshooting the key battery (first thing I tried), it became increasingly clear that our key fob had "bricked" itself either due to a bad board circuitry, antenna module or otherwise (I'll never know as I'm not handy enough to troubleshoot). I also attempted new battery replacement (both the primary and aux) in the off chance the key wasn't the problem.

If this happens, your only solution is to have the vehicle towed to your Mercedes dealer so that they can then open a ticket to order a "First Key," which is more expensive than a "Second" or replacement key (where you already have the primary key in hand that is working with the vehicle). The First Key ships from Mercedes Germany. I worked with Mercedes of Chantilly and they made quick work to get the keys ordered and programmed and all in all from the time I dropped my vehicle to the time I picked up my vehicle it was about 6 business days, which honestly isn't that bad. The total bill came to ~$1,100 for a first and backup key + programming. So an expensive mistake.

And before you say "well yeah, that's your fault," I totally recognize it is, but also wanted to pass along this experience as I had not dealt with it before and if this saves one forum member the hassle and money by causing them to pre-emptively buy that secon/backup key, I've accomplished my goal with this post.

 

You are making me feel much better about ordering an extra key for the BMW I purchased from Hertz. I ordered mine from an authorized BMW parts dealers online (who in turn ordered from BMW Germany) - about $400-500 and no bogus "programming" fee. The key was 100% functional out of the box. Not sure if this sourcing is available for Benz but something to consider absent an emergency situation.

Don't beat yourself up - these keys are absurdly marked up and not always the highest item on your priority list. $1100 for 2 keys sounds about right.

Now I just need to order an extra key for the Hyundai that we bought for my 16 year old...

 

Seriously? $50 per key and another $50 to program them sounds a lot more right to me.

 

Something about this sounds off. Hope an MB mechanic can chime in.

 

I'm surprised by the replies here about this being too pricey. This is the Mercedes tax you hear about. I typically DIY on these vehicles where I can (replaced rear air shocks on the GLS450 after we bought myself to save a huge amount of money - think I purchased the two Arnott bags for $360, versus having the dealer install and mark up parts to the tune or $1,200 to $2,000). However, when it comes to the electrical components and programming of keys, you need to have all of the latest software for the MB Technicans to properly do that. Getting my vehicle up and running quickly is well worth $1,000 to me (just painful it had to happen and that the keys are so overpriced).

 

We had this happen to a sprinter. The Mercedes tax turned out to be 1100 for 2 keys as well. Lesson learned for us was not to loose keys. Hard pill to swallow.

 

Yea unfortunately there is no way for the end user to add new keys. You need a special programming box that the key gets inserted into during the process as well as the specialized OBD-II interface computer to go through the steps, and this equipment together is in the 5 figure range.

 

Keys come ready to go from MB if you do not have keyless go. If you have keyless go, there is still a, I believe 1 in 4, chance it will work. If not, they have to sync the key. The dealership tried to charge me a programming fee on a non-keyless go key. I refused to pay for any programming since it was already programmed from the factory. After arguing for 30 minutes with them, they finally relented and gave me the key without programming. Worked perfectly as all the others have without programming. Wasn't my first rodeo with MB keys. I've lost a few through the washer.

 

Good to know. In my case, our vehicle is equipped with Keyless Go.

 

Mrs B just got the “key not detected” message as she was driving home from airport. She went into a panic as she thought the car would shut down on the freeway. I explained she was ok so long as she didn’t turn off the engine (query what happens with the auto shutoff feature - but I assume that does not shut down the engine)

tBenz really ought to reconsider how they message this issue and fix the software as well

 

I just had a second key fob replaced. Cost about $900! Ouch!