Mbaafc

Hi all,

New to the forum and new to Mercedes, just bought a 2014 e220 cabriolet, absolutely love the car but am having intermittent problems with one of my keys and wondered if anybody had the same and could offer any advice.

I've read A LOT of key problem posts but none that are identical to mine so far so here goes.....

The key seems to work fine and start the car in the mornings but once I've been for a drive get out and lock the car if I go back to the car within a couple of minutes that seems to be when I get the problem, I unlock the car fine the mirrors flash and move the speedo lights up but the rest of the dials and the radio doesn't light up. I turn the key in the ignition it turns but no sign of life at all. If I get out the car lock it and leave it for a few minutes before I try again then it seems to work again or if I use my other key it will work everytime straight away so I'm assuming it's a problem with the ir in one of the keys but wondered if that was likely the problem or not and if I could fix it myself?

The car is still under warranty and booked in with mercedes for a diagnostics check but the soonest date they could give me was over a month away so wondered if I could buy another keyfob and swap the innerds myself before then?

Also as a side note, I noticed a message pop up on the display the last time it happened saying "remove start button and insert key" I understand this is referring to the engine start keyless go button the only problem with that is I don't actually have keyless go so always insert my key anyway.

Many thanks for any advice, am also interested to see if anyone has heard of this same problem too,

Many thanks and sorry for the long post,
Mike

Mbaafc

Just to add sorry, I've tested the ir's on both keys using a camera and can see them both light up if that means there definitely working or not I don't really know!

PaulE550

Did you try putting in some fresh batteries in your key fobs? They could be weak and thus intermittent. Always start by eliminating the simplest potential problem first.

As for buying another key fob, I'm sure MB would be thrilled to sell you another one for around $400 bucks. I wouldn't recommend that as your starting point for troubleshooting this problem though. Just a suggestion.

Mbaafc

I'll be honest, I haven't changed the batteries yet purely because I thought if the lock/unlock and alarm are working OK the batteries must be ok but maybe not.

I also read somewhere that the car should give you a warning if the batteries are getting low, is that not the case?

Thanks for your reply Paul I'll try a new battery tomorrow.

Mbaafc

So I tried a new battery and it made absolutely no difference. Key still locks/unlocks the car but won't start it. Very strange, anybody has any other ideas in the next five weeks while I'm waiting for Mercedes then please let me know!

PaulE550

OK so now you've completely eliminated the only cheap solution to your problem. One key fob still works perfectly all the time and the other is intermittent correct?

Now you are definitely left with the electronics in the one key fob being intermittently defective. Given how you describe the problem occurs, there is either a very small hairline crack or a possible defective solder joint on the little electronics board inside the fob. Neither of which I would expect the average MB service department would be likely to inspect or fix. Someone can correct me if I am wrong on that being the case regarding what MB service personnel do with a typical defective key fob. However, my guess would be MB would just opt to sell you a new replacement key fob.

So at least now you know you definitely need to a new key fob. It would have been a waste of your time going to MB, if the issue had just been resolved with a fresh battery.

Mbaafc

Yeh thanks Paul have to agree with what you've said, I am an electrical engineer and would be happy to take the Key apart and check/repair any solder joints but as the car is still under warranty I'm expecting this to be covered anyway no?

Even if it's not covered by the mb warranty the dealer I bought the car from has already agreed to cover the cost. It's just frustrating I have to wait five weeks for my mb appointment and then probably have to wait for a new key fob to be ordered after that I imagine. Oh well, me and the other half will have to share a key until then I guess.

Thanks for your help!

tw8715

This just happened to me. The first thing the dealership checked was the keys. But that wasn't the problem. The problem was some locking mechanism that let the car knows that its your smart key that wants to start the car. The part unlocks the car so it can start.

My keys still unlocked the doors and did everything except start the car.

Part was around $500 and labor was around $900.

Took 3 days for part to come as it only works with your VIN number car.

Hope this helps!

Mbaafc

Hi tw, thanks but I'm assuming both your keys stopped working right? One of my keys still works fine so makes me think the car must be working fine and it's just one dodgy key I have? Or is that not the case?

tw8715

Oh, Im sorry I didn't read your thread that closely. Yea if 1 key works and the other does not it probably a dead key which would be covered under warranty for the most part. Good luck with the fix!

Mbaafc

Just an update incase anyone has a similar issue. Took the car to Mercedes, they kept it two days and then said they couldn't find anything wrong and so couldn't give me a new key under warranty, I went to collect the car and same problem happened again right outside the dealership so showed them and they then agreed to order me a new key. They said it would have been £330 if it was outside of warranty!

PaulE550

Lol. You have to love the default NTF response from some dealerships. Bet they tried your old key once or twice over the whole two days they had the car. At least the problem re-occurred right outside the dealership, so they couldn't continue to claim nothing was wrong wit the FOB. Congrats on getting a replacement key under warranty.