The car owners of today are living in the future. Today’s cars can unlock themselves when you walk up to them, don’t have keyed ignitions, can be summoned to your position, and can even be controlled by the smartphone everyone has in their pockets. Modern cars are crazy intelligent and scary complex, and unfortunately, that can also hurt you. See that glorious key fob that your car uses? If you lose that on a road trip or even at home, you can be screwed big time, from being stranded for days to shelling out a shocking amount of money for such a small part.
Last week, I discovered a major downside to the smart key fobs that countless new cars in America have today. I will be telling that story as part of a multi-part series, but for now, I want to focus on the small device that, when I lost it, resulted in one of the worst 12-hour periods of my entire life. I lost a key to a brand-new 2025 Ford F-350 Super Duty dually, and I wasn’t prepared for what happened next.
What happened to me could happen to anyone, and what follows that simple mistake can lead to huge heartache. Saying it could happen to anyone is not hyperbole, either, as everything from Kias and Harley-Davidsons to Polaris Slingshots and Chevrolets use fobs and they usually suck to replace in an emergency situation.
Making Keys Smarter
Take a look at the keys on my workbench here. They represent multiple generations of a similar idea. On the left is a key to a 2025 Ford F-350 Super Duty. As you can guess, to the right of that is the key to a 2025 Polaris Slingshot. From there, you have the key to my 2007 BMW 530xi, and finally, the key to my 2008 Smart Fortwo.
I will start with the key on the farthest right. That’s an old-style key fob where the key is physically attached to the remote and is required to slide into a keyed ignition. The common term for a setup like this is “keyless entry” and it’s been around for decades. As Car and Driver notes, the 1987 Cadillac Allanté used an early example of this technology. The car had physical keys for the ignition, but also came with a separate radio-based remote control that locked and unlocked the vehicle’s doors without keys.
This basic sort of setup has evolved over the years. Remotes became integrated into keys, and then some of these keys got really fancy by adopting a clean style where the key wasn’t exposed until you hit a button, exposing the key like a switchblade. Check out the keys to one of my Volkswagens above.
An interesting evolution of this idea is what you see with my BMW’s key. This looks like the remote to a newer car, and sure enough, there isn’t an exposed key. This key is almost a bridge between the simpler technology I just mentioned and the smart key. This key works like my Volkswagen’s key in that I still hit buttons to lock and unlock. But then things get weird when you get into the vehicle because you have to insert the fob into a slot before the start button will work. So, it’s not a physical key, sort of, but it still functions like one.
Then you have the key for the Polaris Slingshot, which is another radio-based key fob. There’s no ignition switch, but it won’t “unlock” as you walk up to it. Instead, you get into the vehicle, hit the unlock button to disable the vehicle’s immobilizer, hit the start button, and you’re off to the races.
How Smart Keys Work
The Ford key is what is known as a “smart key.” The invention of this technology for the mass market is often credited to Siemens. In the 1990s, Siemens created a plastic card that works as a transponder. Here’s a bit from Automotive News:
The technology worked by emitting a low-frequency signal as the driver approached the vehicle. The signal also could configure seats, steering wheel and mirror positions, along with audio presets and temperature settings according to the user’s preferences. As the driver pulled the door handle, the identification card and the car’s security system communicated on a two-way basis, granting permission to unlock the door. With the card still in the driver’s pocket or purse, the vehicle could then be started with the touch of a button.
Depending on the model, the vehicle could be locked by pressing a point on a door handle or simply walking away. Overrides built into the system could identify the driver even if two people with Keyless Go cards approached the vehicle. To ensure security, the keyless device had 4 billion possible security codes that changed randomly each time the vehicle was entered.
Siemens also included an safety attribute that proved attractive to vehicle owners. The Keyless Go device had to be inside the vehicle to start it. At the same time, it also prevented the door from locking if the card was inside but the driver was not.
Mercedes-Benz introduced this technology as an optional upgrade for the 1998 W220 S-Class under the trade name of Keyless Go. Enthusiasts from benzworld.org say that this is how it works in a W220:
The inductive antennae in the doors, in the rear, in the luggage compartment and in the rear bumper are actuated by the Keyless Go control unit.
Their electromagnetic fields cause the transmitter key to transmit its authorization code via radio to the right antenna amplifier module. The transmitter key used last is interrogated first. In addition via these antennae it is established whether transmitter card is outside or inside the vehicle. The body sheet metal attenuates the antenna fields in the outer area limiting the range in a defined manner. The range of the antennae outside the vehicle is approx. 1 – 1.5 m. As a result the transmitter card outside the vehicle can always only be reached by the antennae on one side of the vehicle.
On the other hand, these range sectors overlap in the interior. This defined range limitation allows the Keyless Go control unit to decide whether the transmitter key is located inside or outside the vehicle.
Present-day smart fobs work similarly to this, relying on antennae in the vehicle and a radio pulse generator in the fob for communications. Depending on the model, the vehicle may also have touch capacitive surfaces, such as on the door handles, which will lock or unlock the vehicle so long as the fob is present.
Smart keys have some great advantages. You never actually need to brandish the fob to drive your vehicle. You just walk up, watch as the doors automatically unlock, watch as the vehicle adjusts the seat and mirrors to your settings, hop in, and drive away with only a push of the start button. Vehicles with smart keys are also a little harder to steal than ones with old-school keyed ignitions. You also don’t need to worry about the ignition wearing out or your heavy jailmaster key set shutting down your ignition.
Perhaps the best part of a smart key is the fact that you cannot lock it in the vehicle. So long as the vehicle detects the fob, it won’t allow you to lock the fob in the vehicle! That’s brilliant. I’m sure everyone has a story about locking a key in a car and having to call a locksmith to pop a door open.
Modern Problems With Modern Solutions
The risks are also bigger with fobs. Let’s talk about road trips. In the past, losing your vehicle’s key during a road trip was a headache, but not the end of the world. Because ignitions utilized physical keys, losing your key meant that your car was already parked somewhere. In this road trip scenario, this allowed you to check the immediate area for where you left the key.
If you were unlucky in finding the key, you might have lucked out by just calling out a locksmith or the dealership. Sometimes, you got back on the road with nothing more than giving the dealership your VIN. They’d then cut you a new key, which might have cost you up to a couple of hundred bucks if it was a chip key.
Back in the day, automakers also sometimes made only a handful of key permutations. Because of this, it was perhaps rare, but entirely possible that the key that started your old Ford Ranger also started your Econoline. I remember a time when my mom accidentally “stole” a Ford Windstar because her key worked in a Windstar of a slightly different color. It also meant that locksmiths and shops were able to keep a master key set around to cut new keys from.
Unfortunately, or I suppose fortunately in some cases, modern keys do not permit the shenanigans of the past.
Let’s look at my Smart Fortwo’s key. This is an old-style deal that isn’t as intelligent as Ford’s key. Yet, replacing it can be a major pain. If you lose your Smart Fortwo’s key and happen to have the second key on you, that’s not a big deal, as a locksmith or hardware store can just clone that key. You might pay a few hundred dollars, and everything will be fine.
However, if you lose that key while on a road trip, or lose all keys, now you’re screwed. The Mercedes-Benz dealership will demand that you have the vehicle towed in so that the dealer’s techs can replace both keys and the computer on which the keys are stored. This will cost you well over $1,000 in parts and labor at dealership prices. This comes from my personal experience being in the Smart community for nearly two decades.
The alternative would be to remove the Signal Acquisition Module from your Smart and ship it to SOS Diagnostics in Oregon. They can pair new keys to your existing computer for half the price of the dealer. But there’s the rub. You have to ship it to Oregon, wait for the company to work its magic, and then wait for the computer and keys to get back to you. That’s no help at all if you lost your key on a road trip.
Losing A Smart Fob Can Be A Nightmare
The process with smart keys is somehow worse. Until now, I’ve described situations where a lost key leaves you stranded wherever you last parked your car. However, the main benefit of a smart key is also its weakness.
Say you put your smart key on the roof of your car while you’re putting your baby in the backseat. Now, because you’re a stressed-out and tired parent, you hop in the car, forgetting you put the fob on the roof. However, because the fob is within range to permit vehicle operation, your car allows you to start it up and drive off. Your key then slides off the roof, never to be seen again.
Something I’ve noticed is that not all cars will warn you about this right away. In my case, with the F-350, the truck didn’t warn me about the missing key until I came to a complete stop and put it in park. If your key is lost on a highway, that could be several miles before you’re even made aware of the key’s disappearance, reducing your chances of ever finding it.
Our secret designer, the Bishop, told me his neighbor’s story. His neighbor had a Chevy Tahoe with a smart key. They then drove this SUV almost to Saint Louis, Missouri, from northeast Illinois. It wasn’t until his neighbor got to a rest stop at the western end of Illinois that they noticed that they didn’t have their key. Yep, the SUV let them a few hundred miles without a key. How did this happen? The key was hanging in the laundry room and had just enough range to convince the engine to start, even though it wasn’t in the vehicle.
The saddest part is what happens next. When your vehicle finally gets around to notifying you about your screw up, it may intentionally brick itself the second you put it in park. Then, you’ll be stuck wherever you are. The engine will not start, and in the case of my Ford loaner, even accessory power gets locked out. That means if you have the windows up on a hot day or the windows down on a rainy day, there’s nothing you can do about it.
Now, some manufacturers do offer a backup. According to my conversations with Ford, the FordPass phone app can allow for emergency use of the vehicle ignition without a fob. However, the vehicle can be paired with only one person at a time. If you are not the person who originally registered the vehicle, as would be the case with a press vehicle, a rental, a secondhand vehicle that hasn’t had its data wiped, or borrowing someone else’s vehicle, you’re screwed again. You’re also boned if your phone dies.
The pain continues when you replace the key. When I lost the key to the Ford F-350 in Maryland, I did not have the second key. Motor City Solutions had the second key in Detroit. Unfortunately, since the second key was not with me, the dealership couldn’t just clone the key. Of course, if I had the second key, I wouldn’t have been stranded in the first place, so that’s pretty much a paradox.
Instead, the Ford dealer said that I had to tow the vehicle in. Then, they would access the truck’s systems. But there was a twist. I was informed that due to how the immobilizer system is programmed, the existing surviving key would need to be present to add a single new one. Otherwise, they would need to start with two new blank keys and program both. The original second key, which would have been in Detroit, would be deleted from the truck and no longer work.
In other words, many dealerships treat the loss of a single smart fob during a road trip as being the same thing as losing both fobs. I’ve called around to different Ford dealerships, and it seems the going rate is about $400 to $500 per key, including labor. Since both keys are required here, that means $800 to $1,000 to get back on the road again, though sometimes I’ve heard even higher quotes of closer to $1,300.
Of course, things get even more expensive if you have to tow your vehicle off the side of a highway. I was also lucky enough to have this issue happen on a weekday. Lose a key on a weekend or a holiday, and you can be stuck for days.
Not All Bad
Thankfully, there are ways around these high prices. If you have just lost one of your keys, you can buy a spare online for cheaper than dealership prices and either pair it to your vehicle through DIY or a locksmith. The problem is losing the key during a road trip. In this situation, you don’t really have the luxury of buying a cheaper key online and then shopping around for the cheapest way to get it programmed. You’re sort of just stuck with whoever is willing to help you.
In my case, I was given two choices: I could either pay the dealer big money to replace both keys to the Super Duty, or have Motor City Solutions send out a driver with the spare key in hand. I chose the second option, which took about 9 hours. Of course, my situation was special since it was a press truck.
All of this is to say that losing your modern smart key is just a huge headache. Your vehicle may allow you to drive a surprisingly long distance before effectively bricking itself. Then, you might have to pay some huge dollars to fix your mistake. That being said, there are still lots of great things about smart keys, so I still like them. But I would definitely recommend guarding your smart key like it’s a kid, or maybe even use an AirTag. Don’t let it out of your sight!
As for my story of misery, stay tuned, because it’s going to be a wild and stupid ride.
how about I once locked my CX-9 mazda with my E28 BMW key inside, and that E28 had the Mazda key in it! cx-9 allows you to lock and alarm the car with just a push of a lock button on the door. so unforgiving.