Lost Car Key

What to do if you’ve lost your car keys

There it is. That sinking feeling when you realize you’ve lost your car keys. If you have another key somewhere, it’s not as bad. You can have your partner or friend bring it to you and then we can make you a spare key to replace the one you lost. But what if there was only one key for the car, and now it’s in the ocean, or the back seat of an Uber, or lost down a storm drain. What now? How do you make a copy when there’s nothing left to copy? Don’t worry. We can produce a new key for your car with nothing but a VIN number and proof it’s your car.

If you’re in Berkeley, Emeryville, or Oakland, give us a call. If not, read on anyway. It never hurts knowing a bit before you shop for a service, and this information is true whether we’re doing the work or someone else.

lost car keys laying in the street

If you still have a key for the car

Don’t delay. Get a new key made while you’re still thinking about it. It’s important because making a key without a key is more expensive. Plus you’ll need to tow the car.

Another issue is the missing car key. Could it be where somewhere that it could be found? Could it have been stolen rather than lost? This is especially important if the key was lost in a bag with other identifying material. Anything with an address could lead a thief to your car.

Assuming your car is less than 15 years old, the car likely has an immobilizer. Almost all cars 2005 and newer do. We can erase the lost key so it will no longer start the car. The lost key can still open the doors and trunk, but that’s it.

We can use your old key to “tell” the car that we have the ability to start the car. The car will “know” we’re not trying to steal it, since we can already drive it. The car will then “trust” us to make a new key. But what if we can’t gain the car’s trust with a working key? Well, we’ll need to make the immobilizer think it’s new. When the immobilizer ECU is new, it’s waiting to learn about new keys. It trusts everyone. This is called a seed reset.

Seed Reset

What you’ll need to bring

There are several methods to make a new key if you’ve lost all of your keys. The procedure and cost will vary depending on what type of car you drive but one part of the process is always the same, proving you own the car. In order for us to make a key, you’ll need:

  • A driver’s license
  • At least one of the following with the same name as driver’s license: registration, insurance ID card, insurance policy documents, or vehicle title (pink slip)
  • The car almost always must be towed to the shop
  • A signature confirming that you are indeed authorized to make a key for the car

There is no wiggle room here. Even if we are certain you own the car — let’s say we know you by name and you’ve been bringing the car here for 10 years — it doesn’t matter. For every code or immobilizer pin request we make we must provide documentation to NASTF. If we fail to do so, we lose our license.

We can make a new key for any Toyota, Honda, Subaru, including smart keys, laser cut keys, and remote keys. However, we don’t any mobile work. You’ll need to tow the car here. Sometimes the tow bill plus the key will be less than the service call. Sometimes it will be the other way around. Call for prices and compare. Our number is 510-540-7093 .

There are several mobile locksmiths in Berkeley:

Rex Key

Reed Brothers Security

AC Lock

About the Process

Old Cars

Very old cars (pre-1998) only need a physical key. For most of these we can purchase an indirect key code from the manufacturer and cut a key that will work for your car, provided the locks haven’t been changed at some point in the life of the car.

Less old and new cars

All modern cars have an immobilizer system which adds a layer of complexity. Not only do we need to make a key that will turn the lock cylinders, we’ll also need to create an RFID chip that has the ability to “unlock” the immobilizer system. The immobilizer system prevents the engine control unit from adding fuel to the engine when it’s active.

1998-2003 Toyota Immobilizer System

Older Toyota vehicles (1998-2003) must have a working key to program a new key, which obviously creates a problem if you’ve lost all of your keys. The official solution is to buy a new immobilizer ECU that comes in “auto registration mode”, and will automatically register with the engine control unit and any new keys that are used. Unfortunately these often cost well over $1000 for the part and are placed in deliberately difficult to access areas under the dashboard. Fortunately we can usually either pull an existing key value from the immobilizer ECU, clone a key to that value, and then use that key to register additional keys. If that doesn’t work, we can remove the immobilizer ECU, remove the cover, find the chip with the immobilizer data, and then rewrite the data to its “virgin” format, with the same data that is written to the chip when the ECU is new and in auto registration mode. If none of that works, there’s always the option to buy a new immobilizer ECU, but most of the time we won’t need to.

Most 2004 & Newer Cars

Most newer cars have immobilizer ECUs that can be reset to the “like new” virgin condition via the OBDII port with the factory scan tool and a code we purchase from the manufacturer. This is great news if you’ve lost all of your keys because it’s way cheaper to deal with, although it’s always easier if you have an existing key, so it’s a good idea to have at least two keys for every car you own.

Smart Keys

Smart keys aren’t much different than the regular immobilizer keys, except that some require a little more work. All cars with smart key systems are new enough that the immobilizer ECU can be reset via the OBDII port by a licensed locksmith.

So how much does it cost to make a new key for your car if you lost your key? It depends on the type car and goes up and down with the price of keys, which for the more expensive smart keys can actually vary substantially month to month.

Call 510-540-7093 and we can give you a quote for your car.


Q: Can you come to me so I don’t have to tow the car?

A: No. Sorry. Try one of the mobile locksmiths.

Q: Can I bring my own key?

A: No. Sorry. Picking the right key for a car is actually quite difficult. We’ve tried to accommodate many times, and most of the time it works out poorly for everyone involved.  There are differences in chips, FCC IDs, board numbers, button functions, keyways, and a lot more. We have spent a lost of time trying to get the wrong key to work with a car because the chip or FCC ID, or one of the buttons in incorrect. Even if you do manage to get the right key, there’s still a problem for us — we make money selling keys and don’t have labor priced to cover our costs without parts profit. We have a hard and fast policy now — no customer supplied keys. No exceptions.

Q: Can I email my proof of ownership?

A: NASTF says that a faxed copy isn’t acceptable and we interpret that to mean email isn’t either. We need to photocopy the actual document.

Q: My key was stolen. Can you change the locks?

A: Yes, we can re-key your existing locks so that the old key won’t work anymore. However, if you have an immobilizer system, we will be deleting all keys so the old key won’t start the car anymore. The old key will open the car though and release the steering lock. It’s up to you to decide whether the cost of re-keying the locks is worth the extra money.

Q: Are there any cheaper options?

A: Yes, there often is a cheaper way to go. Usually you’ll need to trade something, appearance, function, longevity, or wait time to order parts, but we can often come up with a cheaper way for you to start and open your car. If cost is a concern, let us know and we’ll look into options.

Q: Do I need to buy two keys when I’ve lost all my keys?

A: It depends on your car. Some cars (Mazda/Ford) require registration of two keys after a reset. With other cars only key is required. We’ll do whatever you want as long as it’s possible, but a word of advice — it really makes sense to have at least two keys for your car.