Merlin1

10 months no problem then this morning no keyless entry or keyless start, did MB come up with a fix for this?

StanNH

No fix ... it just happens randomly every once in a while. Sometimes it will reset with a press of the lock or unlock button on the fob. The unlock function will always reset on its own within one or two minutes of a communication error.

Some have suggested that an occasional manual start of the car with the fob will prevent this from happening. This Keyless Go malfunction has also been reported on other models in the Mercedes line, so it appears to be a problem with the firmware being used.

Some have blamed the close proximity of a smartphone for the error, but I have personally not found that to be the case. Could be some sort of an external RFI issue, but I don't think anyone really has an answer.

ClifordS

I'm told that the battery in the remote last about 10 months....

StanNH

If the battery is low, you will get a warning on the car's main display. I have found no correlation between the battery and this type of malfunction ... and I have seen this happen several times with fresh batteries.

ArifuzeToLose

this **** happens to me all the time, opening manually is too hard. So slide out the metal key from the keyfob and turn it 180 degrees and put it in backwards. This pops the battery cover open, take out the battery and put it back in place. Always fixes the problem for me.

ClifordS

Another thing that can go wrong. I guess that's the tech world we live in.

Merlin1

I fitted new battery about 2 months ago.

Merlin1

Two weeks since keyless stopped working then this morning works, oh the joys of W205.

jolt8631

Don't tell me.... Just before the car was due to go into the dealership?

Unusual, TBF, for the issue to remain consistent. Most report it will fail, seriously, then start working again within a very short period of time.

nbkvig2

Just had this problem arise on my 15 C300. Right now the keyless-go feature is completely dead on the spare key. The other Key works perfectly fine. I've removed the keyless go and used manually and then put the keyless go button back on and spare key still does not work. Unlocks/Locks car perfectly fine (button), but car is simply not "detecting" that key when I try to use any of the keyless go features (engine start button, keyless entry unlock/lock"). Has anyone had similar problems? Feels like it may be isolated to that spare remote rather than the system itself since the original key works fine.

Also, can I take the car into any MB dealership to have them looked at or reprogram the remote under warranty? The dealer I bought the car from is currently inconveniently out of the way.

jolt8631

Might just be wise to p op a new battery in, before taking to the dealership, anyway, just to avoid any "red face" moments.

Any dealer should undertake warranty work for you.

nbkvig2

Thanks for your input! I in fact did avoid a red face moment hahaha. I just took the battery out and put it back in, thought what the heck just try it one more time. What do you know, now it works perfectly fine...if anyone else is having the same issue, I recommend doing the same.

rustycruiser

Lol. I joined the club.

1.5 years, never an issue. Now, neither key can be detected for either opening the doors by touch, or the stop/start button.

Both keys lock/unlock via remote, and physically start the car. Changed the battery in both, still no keyless access or keyless start,

Back to the dealer for the eleventy millionth time I guess.

StanNH

My car started doing that and I took it in. The dealer did find a communications error code and applied a software update. That was several months ago and it's never done it again.

BenzC400

I had the exact same issue. A software update fixed it. Flawless operation since the update.

PeteInGilroy

I only had the issue once and reported it during my Service A. Dealer said they couldn't duplicate it.

After that I had the issue 3 time in one day and made a video. Showed that to the dealer and they did the software update during the wrist pin repair.

Hasn't happened since, but it's going back to the dealer for a hesitation issue after the wrist pin repair. Hope it's something simple.

T.O_c240

Had the error message "Key Not Detected" yet was still able to drive like 300 feet at low speed in a parking lot. I tried pressing the lock/unlock button and waving the key around inside the car like an idiot but it never detected it so one time I turned the car off and on and the other time I popped the push button out and manually turned the key - car turns off when you insert the key then as you turn it to the on position it starts. Happened to me maybe 3-4 times within 6-7 months of driving.

StanNH

The manual ignition switch will work even if the fob is not detected. The typical failure to detect the fob is very random and can happen any time. Sometimes just the doors are affected, sometimes just the ignition, and sometimes both. Usually, full function will return on its own within a few minutes. Some have reported that manually hitting the unlock button will work, but I never found that to be the case.

I have owned two new 2015 C300's, and had a C300 loaner for two weeks. All, at some point, had the problem. My current C300 is the only one that threw an error code. Once an error code is recorded, there is a specific software update which successfully addresses the problem. If that code is not there however, many dealers will not do the necessary update.

Razzyh

When this happened to me, I needed a new key. From Germany only.

snew0172

I have had this problem for over a year on my E350. Have been to the dealer several times. Replaced batteries, no help. Read computer error log, no help. Software update, no help. They finally said there was an issue with static electricity when putting keys in your pocket and pulling them back out. They ordered some leather covers for the key fobs. It has helped but has not fixed the problem. Pressing the unlock button always re-syncs the fob and it starts working again. Very frustrating. I have a Toyota RAV4 with keyless start. Absolutely no problems. I think they know there is a problem with the design of the fob but they don't want to admit it. Has anyone had this problem and second, was there any solution that fixed it?

GerritKw

In my C350e with keyless start and keyless entry i didn't have any issues since October 2015.
That to me does not look like a structural problem then.
I guess it's just bad luck when you have issues.
Judging from all actions so far, maybe the antennas are poorly connected or there is another hardware issue.
I would chase my dealer till its fixed.

eddieo45

Huh??

edit: I looked it up on YouTube. 13 years of Mercedes keys had me thinking I knew how it was done! The new process is a breeze, and only one battery, not two like all my others. No wonder it died so much sooner.....

snew0172

On the last trip to the dealer they replaced one of the key fobs. No problems now for the last 3 months. I haven't tried the fob they didn't replace. There may have been 2 problems with my E350. I think they replaced some unit under the seat and on the last visit they did replace one of the fobs. The replaced fob seems to have finally fixed the problem. It is hard to know exactly what they have done as replacement parts are not showing up on the NC invoice I have received. I am keeping my fingers crossed. Cheers!

ahmadwazim

I have Mercedes c220 d 2015 and had this problem. It appeared few days ago, I changed the battery of key and tried with spare key as well. Then I read in this forum to remove the positive charge cable of main battery for few mins and then try. I did the same and now my keyless is working again. Please try this trick and hopefully it will fix the issue and save you some money
waz

progonat

I confirm that disconnecting the battery can fix this problem. If it doesn't, you will find a lot of great tips here: https://www.youcanic.com/wiki/key-no...wont-start-fix