Smart Car: Find the Mechanical Keyhole for Emergency Entry

When You Need the Mechanical Keyhole

The remote transmitter in the key fob normally locks and unlocks the doors through the central locking system. The mechanical key is the backup for when that fails. Common reasons include:

A dead or weak battery in the key fob; A discharged 12-volt vehicle battery, which can disable central locking entirely; Radio interference or a damaged remote; A fault in the car's locking system

In all of these cases, the physical key and lock cylinder bypass the electronics and let you open the door by hand.

Step 1: Get the Mechanical Key Out of the Fob

Most smart fortwo keys combine the remote and the metal blade in one housing. On many versions, the blade flips out when you press a release button on the fob. Other designs hold an emergency blade that slides out after you press or slide a small catch. If you can't see how your key opens, look for a button or latch on the side or end of the fob. Don't pry the casing open, because you could damage the remote electronics.

Step 2: Locate the Keyhole on the Driver's Door

Start at the driver's door handle. That is the usual location for the emergency lock cylinder on smart cars. Many cars have a mechanical lock only on the driver's side, so don't expect a keyhole on the passenger door or the tailgate unless your manual shows one. Where to look depends on the generation:

Generation (US market) | Where to look | What you may see; 451 fortwo (about 2008–2015 model years) | At the driver's door handle | Typically a visible round lock cylinder; 453 fortwo (2016 model year onward) | At the end of the driver's door handle | Possibly a cylinder hidden behind a removable cap; confirm in your manual; Other or imported smart models | Driver's door handle area | Varies; check the owner's manual for your car

If the handle area looks smooth with no visible keyhole, the cylinder is probably behind a trim cover. Look for a small slot or notch on the underside or edge of the cover. Manufacturers often add this slot so you can release the cap with the tip of the key blade.

Step 3: Remove a Cover, If There Is One

Find the release slot or notch on the cap, usually on its lower or rear edge. Insert the tip of the key blade gently and lever or slide the cap off, following the direction your manual describes. Hold onto the cap so it doesn't fall or get lost. Avoid screwdrivers or other metal tools, which can scratch the paint or break the clips.

Step 4: Unlock and Open the Door

Insert the key fully into the cylinder and turn it in the unlocking direction. The manual shows which way to turn. Then pull the handle to open the door. If the lock feels stiff, move the key back and forth gently rather than forcing it. Cylinders that are rarely used can seize from dirt or corrosion. If the key won't turn at all, stop before you bend or snap the blade. A locksmith or dealer can deal with a seized cylinder.

What Happens After You Get In

On many cars, opening a door with the mechanical key while the alarm is armed sets off the alarm. The alarm normally stops once the car recognizes a valid key, for example when you switch on the ignition with your key. The exact behavior differs between models, so your manual is the best guide.

Opening the door doesn't mean the car will start. The immobilizer is an anti-theft system that only lets the engine or electric drive start when it detects an authorized key, usually through a transponder chip in the fob. A key with a dead remote battery can often still start the car, because the transponder may not need that battery. A blade cut to fit the lock but not programmed to your car will open the door but won't start it.

The ignition is also easy to look for in the wrong place. Earlier smart fortwo generations put the ignition switch on the center console between the seats instead of on the steering column, which surprises many first-time drivers. Later generations moved it closer to the steering column. If you can't find it, check the console area before assuming there's a fault.

Things That Are Easy to Mistake for the Keyhole

Door handle trim caps without a cylinder behind them. Check the driver's side first, since that is where the lock usually is. The fuel filler or charging port door. It is a separate panel and doesn't contain the door lock. Tailgate or rear glass release buttons. They are usually electric and won't work without power or a remote signal. Rubber plugs or drain holes on the door. These are not lock access points.

If the Key Is Locked Inside or Missing

The keyhole only helps if you have the key. If the key is locked in the car, lost, or broken, you have several options:

Roadside assistance: a membership plan, your auto insurance, or a manufacturer warranty plan may cover lockout service. Automotive locksmith: many can open smart cars and cut or program replacement keys. Dealer or authorized service center: they can supply keys and handle key programming for the immobilizer.

Expect to show proof of ownership before anyone opens the car or makes a new key. Usually that means a photo ID together with the registration or title. Reputable locksmiths and dealers ask for this to keep keys out of the wrong hands. Keep your registration somewhere you can reach when the car is locked, such as a photo on your phone.

Avoiding the Next Lockout

Practice removing the key blade and opening the keyhole cover now, so you aren't learning it in the rain or the dark. Replace the fob battery at the first sign of weak range. Try the mechanical lock once in a while so the cylinder doesn't seize. Keep a spare key somewhere secure, not hidden on the car itself. If the car will sit for a long time, maintain the 12-volt battery so central locking keeps working.

In short, the emergency keyhole on a smart car is at the driver's door handle. On some generations it is hidden under a cap that the key tip can release. The blade in the fob opens the door, but only a correctly programmed key will start the car.