Preventing Relay Attacks (Keyless car theft)
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From: Essex Fells, NJ
2016 E400 Sedan, 2018 E400 Cabriolet
Preventing Relay Attacks (Keyless car theft)
You probably have heard of Relay Attacks or keyless car theft. A thief using a radio repeater can steal a car with keyless access in less than a minute even if the owner locks that doors and takes the car keys inside his or her home. The article describes the process.
The owner's manual describes a process to deactivate the SmartKey. (Page 91) When the car is locked using the keyfob by pressing the lock button twice in quick succession, the light on the fob will blink twice, then light once more for about a second. The key fob is now deactivated; therefore, touching the door handles, pulling the trunk release, and waving a foot under the rear bumper, even with the key fob in your hand, does not unlock the doors or open the trunk. Pressing any button on the SmartKey fob returns the keyless access system to its normal functioning. Note that if you have two or more SmartKey fobs, all must be deactivated.
This is much easier and more convenient that putting the keys into a Faraday cage for enhanced security. I've been doing this for quite some time, especially when parked in area where the car might be at an enhanced risk for theft. Thought I'd pass the hint along.
https://www.motoringresearch.com/adv...ow-to-prevent/
The owner's manual describes a process to deactivate the SmartKey. (Page 91) When the car is locked using the keyfob by pressing the lock button twice in quick succession, the light on the fob will blink twice, then light once more for about a second. The key fob is now deactivated; therefore, touching the door handles, pulling the trunk release, and waving a foot under the rear bumper, even with the key fob in your hand, does not unlock the doors or open the trunk. Pressing any button on the SmartKey fob returns the keyless access system to its normal functioning. Note that if you have two or more SmartKey fobs, all must be deactivated.
This is much easier and more convenient that putting the keys into a Faraday cage for enhanced security. I've been doing this for quite some time, especially when parked in area where the car might be at an enhanced risk for theft. Thought I'd pass the hint along.
https://www.motoringresearch.com/adv...ow-to-prevent/
Last edited by fc3; Aug 3, 2020 at 04:23 PM.
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2019 C63CS
Also, for those with newer cars and the latest key fob. There is now a motion sensor in the key fob in addition which disables the fob automatically after 2 minutes if there is no motion detected. So just putting the key down somewhere in the house and not touching it will automatically disable it and it wakes up again as soon as it detects motion. Actually works. Yesterday I was even sitting in my car for over 2 minutes with the fob in my pants pocket while checking something on the phone and when I wanted to start the car it said "key not detected". Apparently I wasn't moving enough and the key disabled itself. Had to shake it to get it to wake up and let me start the car. There are some aftermarket companies that offer motion sensor inserts. They go between the battery and the fob and effectively do the same thing by disconnecting the battery if there is no motion after some time.
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2015 E250 Bluetec
Also, for those with newer cars and the latest key fob. There is now a motion sensor in the key fob in addition which disables the fob automatically after 2 minutes if there is no motion detected. So just putting the key down somewhere in the house and not touching it will automatically disable it and it wakes up again as soon as it detects motion. Actually works. Yesterday I was even sitting in my car for over 2 minutes with the fob in my pants pocket while checking something on the phone and when I wanted to start the car it said "key not detected". Apparently I wasn't moving enough and the key disabled itself. Had to shake it to get it to wake up and let me start the car. There are some aftermarket companies that offer motion sensor inserts. They go between the battery and the fob and effectively do the same thing by disconnecting the battery if there is no motion after some time.
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From: San Francisco Bay Area
2019 C63CS
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From: Dallas-Ft.Worth,TX
2016 E350 Sport
Glad you've clarified this, because this is the W212 forum, and no W212s have the motion detector deactivation feature. My end of model run 2016 with Keyless Go does not have this feature. As OP mentions, one can deactivate the fob manually.
This topic has been discussed several times.
This topic has been discussed several times.
Last edited by DFWdude; Aug 3, 2020 at 05:34 PM.
Out Of Control!!
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From: San Francisco Bay Area
2019 C63CS
Glad you've clarified this, because this is the W212 forum, and no W212s have the motion detector deactivation feature. My end of model run 2016 with Keyless Go does not have this feature. As OP mentions, one can deactivate the fob manually.
This topic has been discussed several times.
This topic has been discussed several times.
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From: Dallas-Ft.Worth,TX
2016 E350 Sport
Yeah, it was more as an FYI for those owning multiple different models, since this topic is universal and I think it's good to know that car manufacturers have responded to the increasing threat of relay attacks at least for newer models. As said, for older models there are aftermarket solutions.
Last edited by DFWdude; Aug 4, 2020 at 02:19 PM.
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From: Dallas-Ft.Worth,TX
2016 E350 Sport
Regarding Faraday cages and such, here is a comprehensive thread on that topic... https://mbworld.org/forums/e-class-w...-security.html
My second key is deactivated and sits in a drawer. My primary key sits within a Faraday cup when at home. Takes less time to use than deactivating the primary key.
My second key is deactivated and sits in a drawer. My primary key sits within a Faraday cup when at home. Takes less time to use than deactivating the primary key.
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From: Dallas-Ft.Worth,TX
2016 E350 Sport
Anytime I deal with an insurance company, it's a nightmare. At my age, I've dealt with more than a dozen different insurance companies, and they are all the same. They will do and say ANYTHING to avoid paying for anything. If your car is stolen, for lack of the thief to yell at, you can be sure the insurance guy will pepper you with a dozen questions making you feel at fault. "Was the car locked and the alarm set?" (in my garage? With the garage door down?} They have no business asking where I keep the keys, but rest assured they will. And the way these cars depreciate, it will be a challenge to prove what the mileage was, etc., unless you documented an oil change the day before it disappeared.
In contrast, dropping my key fob in the faraday cup (based on a metal coffee mug) is no more trouble than hanging the keys on a hook at the back door, or putting the keys in a drawer. The only difference between dropping keys in a drawer and in a faraday cup is the composition of materials (metal vs wood) used by each.
I've parked my car outside restaurants where I can see it from my dinner table... long before I bought my first Mercedes. Just another habit, that's all. A less expensive and aggravating habit than dealing with some insurance claims adjuster who never went beyond 12th grade.
In contrast, dropping my key fob in the faraday cup (based on a metal coffee mug) is no more trouble than hanging the keys on a hook at the back door, or putting the keys in a drawer. The only difference between dropping keys in a drawer and in a faraday cup is the composition of materials (metal vs wood) used by each.
I've parked my car outside restaurants where I can see it from my dinner table... long before I bought my first Mercedes. Just another habit, that's all. A less expensive and aggravating habit than dealing with some insurance claims adjuster who never went beyond 12th grade.
Last edited by DFWdude; Aug 4, 2020 at 05:34 PM.
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2008 E350 4Matic, 2011 E350 4matic
I have had my car stolen, this was a long time ago. Hadn't had one stolen in a long time which why I'm not worried about the relay attack. I don't think that's very popular in the US, it seems to be more common in other foreign countries. Like others said, that's what insurance is for. I used to work for a small company where the owners were all millionaires and once one of them ask me to do some work at her house down the street but that was the time when my car had been stolen and I was just taking the bus to work, took over an hour instead of the 20-30 regular drive. Anyway at the end of the conversation I asked her where the keys were and she sounded surprised and told me that they were in the ignition. I guess all the owners just parked at work with the keys in the ignition all the time. So yeah, I remember filling out the theft report, there's a box for where the keys were, in the ignition or not, and whether the doors were locked or not. So for them, yeah, keys in the ignition, doors unlocked. It was the suburbs though and I don't their cars ever got stolen, I did notice afterwards that they always did that. Oh and my car did get recovered, joy riders, they popped the ignition and broke a small window, took them 2 weeks to find it. Only time the car ever got stolen but every few years, someone breaks a window and tries to steal stuff in the car but there's nothing ever there not even change because I know better. The joys of living in the city.
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You can test if it truly works by locking the car first, performing the double flash routine, then insert your fingers behind the door handle to see if the car unlocks. If it doesn't then that confirms the key is deactivated.
Last edited by DFWdude; Aug 8, 2020 at 07:04 AM.
