Auto-Start!?
Senior Member
Joined: Jun 2023
Posts: 431
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2018 AMG E63s Ed1
This is my top suspected location. I've detailed my car twice in the past year and routinely keep it pretty clean. I removed both front seats last night after I found out it is just the four bolts if you are not removing them from the car completely. When I have more time (and it is not 103 in my garage!) I am going to remove the seatbelt covers to look in there. I took my FOB to see if it could fit in there. It is not easy, but if it fell there and then someone put pressure on it, it can go in there.
Apple uses UWB in their air tags so at least the hardware is there in the iphone's since Iphone 11 none se model... Samsung has Galaxy tags... so if there is a software that can be ran on the phone to leverage the UWB antenna on the phones, it might work in getting you closer to this hidden FOB. Of course what you want to do before you start "sniffing" for UWB is turn off the other FOBs.
How?
Very simple, double tap the lock button. Your FOB has a red light that will flash and then long flash indicating that the FOB is no longer in active mode.
this "feature" will disable the FOBs from transmitting actively which disables the "smart entry". Under normal scenario, to test and make sure that FOBs are "off", try to unlock your car with the FOB in your hand. It will not work unless you press the unlock button. In your scenario, this will not work thanks to the hidden FOB. :/
Now with the other FOB still hidden, now you can sniff for it with the appropriate software.
On an Anecdotal note,
I have seen that "stow away" key scenario happen when someone installs a remote start in these cars. They stick the key usually in the glove box but tape it to the top of the glove box so it is out of the way. This allows for the remote start and remote lock.
Good luck! This is a doozy of an issue.
Last edited by figuwx; Aug 15, 2023 at 02:31 PM.
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 40
Likes: 8
From: GA
E300
otherwise the rear "ashtray" under the vents might be another spot but if it is in none of those and not in the rear seat, the owner hid it on purpose and that will not be found unless you start taking apart dashboards, armreset console.
Apple uses UWB in their air tags so at least the hardware is there in the iphone's since Iphone 11 none se model... Samsung has Galaxy tags... so if there is a software that can be ran on the phone to leverage the UWB antenna on the phones, it might work in getting you closer to this hidden FOB. Of course what you want to do before you start "sniffing" for UWB is turn off the other FOBs.
How?
Very simple, long hold the lock button. Your FOB has a red light that will flash and then long flash indicating that the FOB is no longer in active mode.
this "feature" will disable the FOBs from transmitting actively which disables the "smart entry". Under normal scenario, to test and make sure that FOBs are "off", try to unlock your car with the FOB in your hand. It will not work unless you press the unlock button. In your scenario, this will not work thanks to the hidden FOB. :/
Now with the other FOB still hidden, now you can sniff for it with the appropriate software.
On an Anecdotal note,
I have seen that "stow away" key scenario happen when someone installs a remote start in these cars. They stick the key usually in the glove box but tape it to the top of the glove box so it is out of the way. This allows for the remote start and remote lock.
Good luck! This is a doozy of an issue.
Apple uses UWB in their air tags so at least the hardware is there in the iphone's since Iphone 11 none se model... Samsung has Galaxy tags... so if there is a software that can be ran on the phone to leverage the UWB antenna on the phones, it might work in getting you closer to this hidden FOB. Of course what you want to do before you start "sniffing" for UWB is turn off the other FOBs.
How?
Very simple, long hold the lock button. Your FOB has a red light that will flash and then long flash indicating that the FOB is no longer in active mode.
this "feature" will disable the FOBs from transmitting actively which disables the "smart entry". Under normal scenario, to test and make sure that FOBs are "off", try to unlock your car with the FOB in your hand. It will not work unless you press the unlock button. In your scenario, this will not work thanks to the hidden FOB. :/
Now with the other FOB still hidden, now you can sniff for it with the appropriate software.
On an Anecdotal note,
I have seen that "stow away" key scenario happen when someone installs a remote start in these cars. They stick the key usually in the glove box but tape it to the top of the glove box so it is out of the way. This allows for the remote start and remote lock.
Good luck! This is a doozy of an issue.
Thank you for the "stow away" note. I am starting to think that is exactly what happened. Someone hid the key in the car for whatever reason, maybe thinking it would always start for them before they realized the FOB goes to sleep after X period of non-movement.
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 40
Likes: 8
From: GA
E300
I have not. I'll try to remember that. Can you post a close up so I know exactly where you mean? (end sarcasm font) Do you honestly think I would have taken out both front seats before checking to see if the key was in the key slot? Do you honestly think it could be there for weeks/months without me noticing? If you posted this as a joke, my apologies for not catching on to it.
Member
Joined: Apr 2017
Posts: 87
Likes: 36
'19 E300 w/ activated Multibeam
I have not. I'll try to remember that. Can you post a close up so I know exactly where you mean? (end sarcasm font) Do you honestly think I would have taken out both front seats before checking to see if the key was in the key slot? Do you honestly think it could be there for weeks/months without me noticing? If you posted this as a joke, my apologies for not catching on to it.
MBWorld Fanatic!
Joined: Nov 2014
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.
Because the fob appears to be active especially after moving the vehicle, another option is to use a RTL-SDR dongle with scanner software such as SDR# to look for 415 MHz signals. From that one can check for signal strength as well as triangulate the source location.
A RTL-SDR dongle will cost about $20 if you don't already have one. Thedongles are the same as one uses to feed ADS-B and AIS sites. The software is free.
A RTL-SDR dongle will cost about $20 if you don't already have one. Thedongles are the same as one uses to feed ADS-B and AIS sites. The software is free.
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 40
Likes: 8
From: GA
E300
Because the fob appears to be active especially after moving the vehicle, another option is to use a RTL-SDR dongle with scanner software such as SDR# to look for 415 MHz signals. From that one can check for signal strength as well as triangulate the source location.
A RTL-SDR dongle will cost about $20 if you don't already have one. Thedongles are the same as one uses to feed ADS-B and AIS sites. The software is free.
A RTL-SDR dongle will cost about $20 if you don't already have one. Thedongles are the same as one uses to feed ADS-B and AIS sites. The software is free.
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Senior Member
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2018 AMG E63s Ed1
Senior Member
Joined: Jun 2023
Posts: 431
Likes: 293
2018 AMG E63s Ed1
Senior Member
Joined: Jun 2023
Posts: 431
Likes: 293
2018 AMG E63s Ed1
@DrJonesLaw
Just thought about this.
If the fob has been barking about a low battery. The more than likely solution is that the fob is close to that place indicated above where you usually insert the fob.
That area does not need the fob to have a battery as it will power it enough to start the car. which means disassembling the center console.
Just thought about this.
If the fob has been barking about a low battery. The more than likely solution is that the fob is close to that place indicated above where you usually insert the fob.
That area does not need the fob to have a battery as it will power it enough to start the car. which means disassembling the center console.
MBWorld God!
Joined: Dec 2019
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There is a third key. Now I just need to find it. The third key explains everything. It explains why my car tells me the FOB battery is low despite me changing the battery in both of my FOBs TWICE, first time assuming I got a bad batch of batteries.
It explains why sometimes when I do forget my key the car won't start. (because the hidden third key has been still for X period of time therefore making it go to sleep mode)
It explains why when I do happen to drive somewhere and realize I don't have a key with me I can get back in my car and it always starts. (I always wondered how did it know I was not home and it allowed me to restart the car to go home and get a key)
Dealer confirmed a third key was made for the car without resetting frequency.
So, my belief now is previous owner lost a key. (it fell out of his/her pocket and is under a seat somewhere) and assumed it was gone forever, so they just bought a new one.
I've given it a pretty good college try looking under the seats for the key to no avail. But, it may be wedged in the jumble of wires and relays under the seat so I am going to research how to remove the seat(s) and look for it there. (I'm hoping for my purposes, I can just remove those four bolts) If it is not under the seats, I'll be back at square one. (well, square 3, I am 99% convinced the key is in the car, even if I cannot find it)
In hindsight, I do believe all of the times I have been able to start it "without" the key it was when I got home, ran inside, changed clothes or did some other remedial task and in a hurry went back to the car sans my keys.
It has been quite the mystery. I look forward to finding that missing key somewhere in the sled!!
It explains why sometimes when I do forget my key the car won't start. (because the hidden third key has been still for X period of time therefore making it go to sleep mode)
It explains why when I do happen to drive somewhere and realize I don't have a key with me I can get back in my car and it always starts. (I always wondered how did it know I was not home and it allowed me to restart the car to go home and get a key)
Dealer confirmed a third key was made for the car without resetting frequency.
So, my belief now is previous owner lost a key. (it fell out of his/her pocket and is under a seat somewhere) and assumed it was gone forever, so they just bought a new one.
I've given it a pretty good college try looking under the seats for the key to no avail. But, it may be wedged in the jumble of wires and relays under the seat so I am going to research how to remove the seat(s) and look for it there. (I'm hoping for my purposes, I can just remove those four bolts) If it is not under the seats, I'll be back at square one. (well, square 3, I am 99% convinced the key is in the car, even if I cannot find it)
In hindsight, I do believe all of the times I have been able to start it "without" the key it was when I got home, ran inside, changed clothes or did some other remedial task and in a hurry went back to the car sans my keys.
It has been quite the mystery. I look forward to finding that missing key somewhere in the sled!!
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 40
Likes: 8
From: GA
E300
no. But the only real searching I have done is I removed the front seats to see if it was tucked in there. I strongly believe it is hidden in the dash somewhere and I have not taken it apart to look for it.
I come to this conclusion since I discovered the original owner was car rental place in miami. I have discovered car rental places that allow for drop offs at places other than the original location will hide the spare key somewhere so it is always with the car. The two "standard" hiding places are in the spare tire well and tucked up inside the rear speaker compartment. Some places will put it in the dash somewhere.
I come to this conclusion since I discovered the original owner was car rental place in miami. I have discovered car rental places that allow for drop offs at places other than the original location will hide the spare key somewhere so it is always with the car. The two "standard" hiding places are in the spare tire well and tucked up inside the rear speaker compartment. Some places will put it in the dash somewhere.
Last edited by DrJonesLaw; Jul 27, 2025 at 11:40 AM.
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Joined: Aug 2014
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From: Tennessee
W214 E450
no. But the only real searching I have done is I removed the front seats to see if it was tucked in there. I strongly believe it is hidden in the dash somewhere and I have not taken it apart to look for it.
I come to this conclusion since I discovered the original owner was car rental place in miami. I have discovered car rental places that allow for drop offs at places other than the original location will hide the spare key somewhere so it is always with the car. The two "standard" hiding places are in the spare tire well and tucked up inside the rear speaker compartment. Some places will put it in the dash somewhere.
I come to this conclusion since I discovered the original owner was car rental place in miami. I have discovered car rental places that allow for drop offs at places other than the original location will hide the spare key somewhere so it is always with the car. The two "standard" hiding places are in the spare tire well and tucked up inside the rear speaker compartment. Some places will put it in the dash somewhere.
Have you tried to get contact info for the prior owner to see if they could give you information? I'm assuming you have, but just asking for my own curiosity on what the outcome of that was.
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 40
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From: GA
E300
I just read this thread for the first time. I must say, it's an interesting one. First the mystery of the ability to start the car without a key and now on where this third key could be stashed. I agree that it's unlikely at this point to be an accident to lose the key in the car as you should have found it by now. It could be possible that the prior owner dropped into some place that they could not retrieve it without disassembly to some degree and they decided to just get another one. Another possibility is they intentionally hid it so they could take (recover) the car back if they ever saw it in public. Perhaps their thinking was they could bump or shake the car to wake up the fob and drive away. If the battery is dead on the hidden fob and it's still allowing the car to start then maybe it is close enough to the storage spot or perhaps someone ran a wire to allow the key to be somewhere else and still work without a battery. This is a good possibility if the prior owner was a car rental company and they wanted a way to recover the car. Either way, this would drive me crazy and I would have to pull the center console apart to rule that out. If it is intentionally hidden by the prior owner, I would assume it's not hidden to where a significant amount of disassembly is required. I would be looking in the fuse panel and pulling the under dash panels off to see if it's taped under there somewhere. Basic disassembly needed to run wires for after market electronics would be my focus.
Have you tried to get contact info for the prior owner to see if they could give you information? I'm assuming you have, but just asking for my own curiosity on what the outcome of that was.
Have you tried to get contact info for the prior owner to see if they could give you information? I'm assuming you have, but just asking for my own curiosity on what the outcome of that was.
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no. But the only real searching I have done is I removed the front seats to see if it was tucked in there. I strongly believe it is hidden in the dash somewhere and I have not taken it apart to look for it.
I come to this conclusion since I discovered the original owner was car rental place in miami. I have discovered car rental places that allow for drop offs at places other than the original location will hide the spare key somewhere so it is always with the car. The two "standard" hiding places are in the spare tire well and tucked up inside the rear speaker compartment. Some places will put it in the dash somewhere.
I come to this conclusion since I discovered the original owner was car rental place in miami. I have discovered car rental places that allow for drop offs at places other than the original location will hide the spare key somewhere so it is always with the car. The two "standard" hiding places are in the spare tire well and tucked up inside the rear speaker compartment. Some places will put it in the dash somewhere.
MBWorld God!
Joined: Dec 2019
Posts: 32,495
Likes: 6,347
sorry for any confusion, since the FOB battery died, I no longer have the issue of it being able to start "with no key". I edited a previous comment so you may not have seen it, I have since discovered it was rental car before I had it and I discovered it is not uncommon for rental car companies with multiple locations to hide the second key so it is always with the car. I've already checked the most common places.
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Joined: Nov 2021
Posts: 66
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From: Texas
2017 E43 AMG, 2009 E63 AMG (fuel injector hydrolock, scrapped 2024), 1999 C230 Kompressor (sold)
@DrJonesLaw
Just thought about this.
If the fob has been barking about a low battery. The more than likely solution is that the fob is close to that place indicated above where you usually insert the fob.
That area does not need the fob to have a battery as it will power it enough to start the car. which means disassembling the center console.
Just thought about this.
If the fob has been barking about a low battery. The more than likely solution is that the fob is close to that place indicated above where you usually insert the fob.
That area does not need the fob to have a battery as it will power it enough to start the car. which means disassembling the center console.
You best believe I'm stripping my car down to bare metal, plastic granules, and breathing cows if it meant I had a chance of finding a second (or even a third) key for it. How much do these replacement smartkeys cost again? $2000?
The single key I had for my w211 inexplicably became intermittent and then completely died on me. A local "2001 dodge caravan" locksmith programmed me a new aftermarket key for $200. Right after the key was copied it died and never worked again. I would have been in for an "all keys lost" treatment.
I got bored and reminiscent of my beloved w211 (I lost it tragically...) and disassembled the original key. Almost imperceptible amounts of corrosion caused it to fully cease working. Thoroughly brushed it with alcohol, and it began working again. Lesson learned, always have a second key.
I still don't have a second key for my w213.
MBWorld God!
Joined: Dec 2019
Posts: 32,495
Likes: 6,347
What an interesting thread...
You best believe I'm stripping my car down to bare metal, plastic granules, and breathing cows if it meant I had a chance of finding a second (or even a third) key for it. How much do these replacement smartkeys cost again? $2000?
The single key I had for my w211 inexplicably became intermittent and then completely died on me. A local "2001 dodge caravan" locksmith programmed me a new aftermarket key for $200. Right after the key was copied it died and never worked again. I would have been in for an "all keys lost" treatment.
I got bored and reminiscent of my beloved w211 (I lost it tragically...) and disassembled the original key. Almost imperceptible amounts of corrosion caused it to fully cease working. Thoroughly brushed it with alcohol, and it began working again. Lesson learned, always have a second key.
I still don't have a second key for my w213.
You best believe I'm stripping my car down to bare metal, plastic granules, and breathing cows if it meant I had a chance of finding a second (or even a third) key for it. How much do these replacement smartkeys cost again? $2000?
The single key I had for my w211 inexplicably became intermittent and then completely died on me. A local "2001 dodge caravan" locksmith programmed me a new aftermarket key for $200. Right after the key was copied it died and never worked again. I would have been in for an "all keys lost" treatment.
I got bored and reminiscent of my beloved w211 (I lost it tragically...) and disassembled the original key. Almost imperceptible amounts of corrosion caused it to fully cease working. Thoroughly brushed it with alcohol, and it began working again. Lesson learned, always have a second key.
I still don't have a second key for my w213.
