Jemar Coleman

So my keyless go stopped working. I have to use my key fob to lock, unlock, and start the car. Any suggestions without going to the dealer??? I already did a reset on the key fob and changed the fob battery. When i try to push start, on screen displays key not detected. My vehicle is a 2015 S550 4matic.

valley_isle

I had this happen on my car at about 9,000 miles. I did everything you described above, and then, on a lark, re-booted the COMAND system. I have no idea if that is in any way connected to the Keyless Go function, but it worked and Keyless Go worked again. Just thought I would share as an option to try.

Jemar Coleman

Ok thanks. Will try it

cetialpha5

Do you have a volt meter? Check the voltage on the battery. Lots of times you get old batteries when you just buy them in the store so the voltage is too low for keyless go. Otherwise, you'd have to get a scanner to see if there are any keyless go error codes in the system. Or try the other fob. Same problem, it's the car, if it works fine, it's the key.

Jemar Coleman

Yes i have a volt meter. Ill check it out. I also have a scanner but do i need a special scanner to check for the keyless go?

cetialpha5

You need a scanner that can read MB specific error codes. Most regular scanners only do engine and emissions error codes. There's lots of scanners out there that will do it though and they're typically in the $100-$150 range although you could get a knock off star unit for $600+

I think in general Keyless go is pretty reliable, when it goes, sometimes it's the antenna or control unit. But mostly it's either the battery or the key fob is bad. That's why I say try the other key.

DrDoe

If you don't have a 2nd key then you should go to the dealer and get one for insurance. Having one key is very risky. At the same time, the dealer can do some troubleshooting for you if they can't get the 2nd key to work with keyless go.
Did you happened to run your key through the washer? One of my key stopped working after my wife washed my pants. Yup, that's $500 mistake.
Out of curiosity, today I started the car with the washed key and it worked. I didn't tried that before ordered a new key. It still work but without keyless go. That's interesting.

cetialpha5

You could try and get a can of electrical contact cleaner. Take the battery out and then spray down all the electronics in the key a few times. Basically there's two parts to the key, the electronics powered by the battery and then there's the rfid part which is powered by the car and doesn't need a battery. Going through the washer, it's probably shorted out by whatever residue was in the wash. The contact cleaner might be able to clean out the short and it might work again. Otherwise you're just out the cost of a can of electrical contact cleaner.

https://www.walmart.com/ip/CRC-5103-...Wt-Oz/16817418

DrDoe

With nothing to lose, I went ahead and clean the key fob circuit board. Now the key fob behaves differently. Lock and rear door buttons do nothing. Unlock button would lock the door. Door can be unlocked by pulling the handle so it seems to be seeing the key but the push button starter is still not working.
If I did the key fob cleaning from the start then I could get by with not having to order the 2nd key.

cetialpha5

Did you clean the inside of the key fob also? There's also some circuitry inside that also. Also in some videos, when cleaning the key fob itself, they used qtips to clean the residue off, contact cleaner alone might not be enough to clean it all out. I'd also give it more time to fully dry if you soak the entire outer key fob shell in contact cleaner.

DrDoe

I sprayed the board with electronic cleaner and brushed both sides with toothbrush.
I did it couple of times.
Perhaps it needs DeoxIT?

DrDoe

One other thing which seems strange. Car was unlocked and I was 20feet away from the car. Car went to lock mode when I insert the battery portion into the key fob.
It seems car see some parts of the key...

cetialpha5

Maybe the lock button is shorted so that automatically comes on once you put the battery in.

DrDoe

Makes sense. I think I have enough fun with it for the day. I also tried the key fob relearn procedure. Not sure if there's any codes that can be seen with DAS.

Jemar Coleman

So it was my right rear door sensor for the keyless go that was diagnosed to be the problem. So I paid 180 for the diagnosis, then had to pay 520 plus tax to replace the sensor. My service advisor calls me and says the old sensor fried my keyless go module. Smh then he said that would be 1000 dollars. Thats crazy. Then how come they couldn't diagnose both problems at once instead 1 at a time. I wouldn't have paid the 520.00 if I knew I would have to pay another 1000 for a module.

seamus2154

I'd have a problem with that. They gave you a diagnosis and asked you to make a decision. You did. Then they tell you their diagnosis was incomplete and wrong?? Sounds like they walked you down the path becuase they knew it wasnt warranty and out of pocket.

konigstiger

KG CU current part # 2229004213 list $268 / sale price $88.80 https://www.mercedespartscenter.com/

Door sensor (incorporated into handle) affecting CU sounds odd all fault codes should have been retrieved via Xentry quick test. MB covers repair for 12 months speak to Service Manager to request no cost CU replacement due to misdiagnose.

Thom_w222

have the same problem... did u find out where was the problem? Thanks

joelawyerz

Just in follow-up to the above post about having a second key fob, make sure that the metal key inside the fob is actually to your car! I had to get a rental to drive three hours home and three hours back upon discovering that the fob in my pocket when I jumped in the pool did not actually have the correct metal key. Not a clue how that happened as I bought the car used and never thought to check that the actual metal keys were to the specific car. There was quite a bit of trepidation as I approached my completely locked down as 550 with the second key file, hoping that the metal key actually fit my car. It did, but that would have really sucked. I think the only way to get a replacement key is to prove ownership at a Mercedes dealership and then the order one from the plant in Germany.
PS, even though the soaked key fob wasn't working after I jumped in the pool, I stuck it in a Tupperware box full of moisture wicking material and after a few weeks, it works good as new.

Thom_w222

well the my way thing is that i was driving the vehickle over a year.. that a s550 yr2016.. but now have the same problem.. dont have second key to check... but all the previos time all was good... sick... how to find out where is the problem? Without mercedes service of course cuz they charging for nothing.. finding first not actual problems and taking to much anyway..

BenzNinja

iTrader: (4)

join the BenzNinja Club and you'll safe up to 90%

cetialpha5

I think I've seen that the key comes from some place in Texas. Also there's two keys, the fob itself and just the metal key. You can just order one without the other. The metal key is cheaper, some have said it's only $75 but maybe the price has gone up since.

ATX GLE

I have a similar issue as the OP. Fob works fine when pushing buttons, but not Keyless Go. If you touch the handles while the fob is in your pocket, nothing. However (here’s the odd part) if you hold the fob 2-3 inches from the door handle everything works fine. Both fobs act the same, both have brand new out of the package batteries. And, on occasion the car won’t recognize the fob requiring me to place it in the cup holder. I’ve done the relearn procedure, etc. I’ve read it could be an antenna issue.
Ideas??

Tom in Austin

How long ago did you replace your auxillary battery? I had some of these flaky keyless go problems on my car but haven't seen them again since changing the aux battery. Pretty inexpensive diagnostic step esp if your battery is old and coming up on replacement already.

ATX GLE

That is a great question. I just purchased a new to me GLC63S and am not familiar with the auxiliary battery. Will have to research this. Thx for the advice.