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Can You Lock a Smart Key In Your Car?

Smart keys are are a new level of convenience that have started to come with most new cars. With the press of a button, you’re inside your vehicle with the engine running, moreover, smart keys can also remotely start your car. Since you use a smart key to operate the door locks, though, what happens if it gets left inside the vehicle?

Can you lock a smart key in your car? You can accidentally lock your smart key in your vehicle, even though the car will have systems built in to try and prevent this. Manufacturers have solutions for if this does happen, but you have to know about them in advance.

Even though there are safeguards that make it difficult to lock your smart key in the car (including having a physical key which we’ve discussed previously), it can happen. If you’ve found yourself in this predicament, know there are a number of ways to get it back, including through the manufacturer’s mobile application or via emergency vehicle assistance. Put simply, you won’t be left out in the cold if this happens to you.

How Modern Key Fobs Work

Audi Car Keys - Smaller

A smart key is a small fob that slips into your pocket or purse. It includes buttons that control the door locks and start your car engine. How a smart key works is simple. Antennas in the vehicle’s body receive the signal from the fob and send it to the vehicle’s computer. When the signal is received, a message to perform the task is sent out.

Most key fobs can also control the trunk, and some fobs can start the ignition. Not all smart keys can start a vehicle, and others only work when the car’s immobilizer has been disengaged. How the smart key starts the ignition varies by the vehicle manufacturer.

How close to the vehicle for the modern key fob to work, is also different depending on the company. For example, a Mercedes smart key will automatically unlock the car door when you’re a yard away. While all key fobs work the same, you’ll notice some differences depending on the type of vehicle you drive.

Cars with Backup Keyed Entry

Backup keyed entry is when the vehicle has a keyhole on the outside of the door. This means you have the option of using a fob or a traditional key, in the case the fob breaks down or no longer works for whatever reason. Even though fobs are easier and more convenient, it’s still helpful to have another way into the car. Additionally, you can buy fobs that include a key right on it, such as this one from Toyota (on Amazon).

Since it is possible to accidentally lock your smart key in the vehicle, a keyed entry is a convenient backup. Some smart key systems, like Honda, come with both a fob and a traditional key. Not only is it helpful when the fob is locked inside, but you can also use it for valet parking. Keep the fob with you and give the traditional key to the attendant.

Cars Without Backend Keyed Entry

Not all vehicles have keyed entry points and this can be a problem if the smart fob is locked inside. However, most vehicle manufacturers have already thought of this scenario and have developed alternatives in case it happens to you. Even though several fobs come with hard keys inside small compartments, it’s not uncommon for them to only open the trunk or the glove box.

Everyone makes mistakes, and it’s not uncommon for smart key fobs to get locked inside the vehicle. There are a number of ways this can happen, including by simply forgetting the fob is still inside after getting out, or by accidentally taking the wrong fob assuming you own another one for a different vehicle.

Whatever way you happened to get your smart key locked inside, you can get it back without breaking any windows or going to a locksmith (our guide), but you may have to refer to your owner’s guide to figure out the next step. Some manufacturers will send a signal to the vehicle’s computer to open the doors. Others will send emergency roadside assistance. The nuclear option will be to contact a locksmith and go from there.

Smart Key Differences Between Car Manufacturers

While there are many similarities between vehicle companies, including Toyota, Honda, Chevy, Ford, and Mercedes, the differences between them are important enough to mention. Here’s what to expect from the five major vehicle brands in the U.S. While there are differences from car model to car model, here’s what these manufacturers are doing on most of their newer cars;


Most newer model Toyotas come with a key fob. You can use it to open and lock doors, trunks, and tailgates. If the smart system was factory-installed, it may also comes with a remote start. The maximum distance the car’s computer will receive the fob’s radio signal from is 80-feet. However, there can’t be any trees, utility poles, or other obstacles in the way. There must be a clear path from the fob to the vehicle.


You can unlock doors from 32-inches away with Honda’s smart key and it also locks doors with the press of the button. Some keys come with remote start, though you’ll typically have to use the push button start when you get in still. On some newer models, Honda offers a Keyless Go card.


Control the vehicle’s locks and start the engine from three feet away with the Chevy smart key, which can also manage the liftgates. However, for your car to completely start, your foot needs to be on the brake. It’s a safety measure to prevent the vehicle from accidentally moving without a driver behind the wheel. You can also customize the keyless entry system with the Chevy app.


Ford’s key fob controls the door, trunk, and tailgate locks from around 6-feet away, though obstacles can shorten the distance. The smart key can also start the engine, though it needs to be inside the vehicle. You also have the advantage of ‘sleep mode’ which is a preventative measure against hackers. When the fob hasn’t been in use for 40 seconds it goes to sleep and can’t be used by outside parties.


All Mercedes vehicles come standard with infrared smart key access. Mercedes, who has been credited with inventing keyless entry, has continued to improve on the concept over the years. You can use the fob to manage door locks, roll down the windows, as well as remotely control the vehicle from the exterior or from inside the vehicle. You can also purchase key fob cases that protect it from damage (on Amazon)

With the smart key in your pocket, you can also pull on the door handle and it will unlock. You don’t have to press any buttons, just have the fob close to the vehicle. Keyless Go also lets you start the vehicle without a key. To do this, you just have to press on the brake and the engine will start automatically.


Even though it is possible to lock a smart key in your car, it’s not easy to do. because manufacturers have put safeguards in place. However, if you do there’s no reason to panic since it won’t take long to get you back in. Either call the car company to have them unlock it through their computer system, or call roadside assistance or a locksmith.