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Auto Keys

Auto Keys

If you are curious about your auto keys, they probably aren’t working.

Here are the three most common reasons:

  1. Your car battery is dead.
  2. The battery in the key remote is dead and needs to be replaced.
  3. Your key or key remote has lost its programming.

NOTE: If your key remote has buttons that allow you to perform functions, like locking and unlocking your car door, it is called a keyless entry transmitter. This is what requires a battery. This transmitter battery has no impact on whether or not your car will start.  It simply allows you to perform the functions that are available on your key remote.

There are several types of auto keys in today’s auto market. Most modern auto keys contain a computer chip which is programmed so the car and key can communicate electronically, enabling the car to function. Often they are referred to as immobilizers because they are designed to make it hard to steal a car without the key programmed for that specific car. There are several names for these different types of auto keys, depending on the car manufacturer. Here are  some of the most commonly used names (keeping in mind that your manufacturer may call your key something different). If you know your auto keys aren’t working, click on the tabs below to learn the different types of auto keys and what you will have to do to fix them:

Basic Transponder

NOTE: A transponder is an electronic device used to wirelessly receive and transmit electrical signals.  Technically all keys with a programmed chip would be a transponder. The term seems to be used frequently for these types of auto keys, so we are going to refer to them as a basic transponder key.


Basic transponder key with keyless entry remote built into the key casing.

These auto keys usually consist of a metal key with plastic on top, which is covering a computer chip that is programmed so the key and key remote will work with your car. Sometimes they will have buttons on the plastic covering that allow you to remotely control your car door locks. Others may come with a separate remote for locking and unlocking your doors.

If the battery dies in your transponder key remote (known as a transmitter), you can most likely change the battery yourself. Key remote batteries can be purchased at places like Walmart, AutoZone, RadioShack, or Batteries Plus. You can also have it changed at a dealership or any other type of automotive service shop.

Sometimes transponder keys will need to be reprogrammed. You can program many keys yourself; just do a Google search or check your owner’s manual for instructions. You will usually need to have at least two working master keys to be able to program a third or fourth key. If you don’t have at least two master keys, you will probably need to make a trip to the dealership or locksmith.

If you lose your only transponder car key, you will either need to have your car towed to a dealership, or call a locksmith that has equipment to cut and program transponder keys. If you can find a locksmith that will come to you, it might save some money by avoiding a towing fee . It also depends on the model of car you have; there are some auto keys that can only be programmed at the dealership. You can purchase transponder keys on websites such as ebay or, but double check, before you spend the money, that your dealership will cut and program a key purchased somewhere else. Although purchasing the actual key online may be cheaper, sometimes dealerships will only service auto keys purchased through the manufacturer.

keyless- auto keys

Non-metal basic transponder key with keyless entry remote.

There are some auto keys that do not have a traditional metal key attached, but you still need to plug the “key” into your vehicle for it to start. These keys are not that different from a basic transponder key, except they look different without the traditional metal key. Some have a small plastic or metal key (sometimes referred to as an emergency key) on the inside of the main key that you can slide out. If your car battery or key remote battery dies, you can use this small key to enter your vehicle. You cannot start your car with this key; to start your car you would need the remote which contains the chip. This is also the key that will open your glove box. If you are going to give your auto keys to a valet attendant, you can lock your valuables in your glove box and keep this little key with you. This eliminates the need for a separate valet key.  The same rules apply when troubleshooting or replacing a basic transponder key and a non-metal “key.”

NOTE: Even if you don’t see where to insert your key, there is ALWAYS a place to manually unlock your doors. It is where you would expect it to be on a “regular” car, there is just usually a plastic cover over the cylinder.

Smart/Push Button Start
smart key - auto keys

Smart key

On some cars, you can start your car by simply pushing a button. You must have the key remote with you for the button to work, so not just anyone can get in your car and start it. The remote can be in your pocket, purse, or wherever you want to keep it. The car doors will unlock for you when you get close enough because the car will read the remote. These cars don’t have a visible place to insert a key into the door. These types of auto keys also usually allow you to push a button and start your car remotely, a fantastic feature for those of us who live in a northern climate. They also make it nearly impossible for you to lock your keys in the car. If your keys are in the car, it won’t lock and will make some type of noise to let you know your keys are still inside.

You can usually change a smart key battery yourself. Vehicles with smart or push button start will have a warning signal on your dashboard to let you know when your key remote battery is getting low, so you can take care of it before it runs out completely. If the buttons on your smart key quit working (for example lock and unlock), you can sometimes program them yourself, although some will have to be programmed at the dealership. A quick look in your owner’s manual or a Google search should provide you with instructions, if self-programming is possible. You will probably need two keys in order to self program.

If you need to replace your key, there are some brands, like Mercedes, that cannot be programmed twice. Make sure you don’t purchase a used key and then find out it’s useless. If you need to get a smart key replaced, you will have to go to a locksmith or dealership.

NOTE: Even if you don’t see where to insert your key, there is ALWAYS a place to manually unlock your doors. It is where you would expect it to be on a “regular” car, there is just usually a plastic cover over the cylinder.

valet key with non-metal transponder key - auto keys

The metal key on the left is the valet key that is stored inside the non-metal transponder key.

A valet key is a key that will open the door and start the car, but it won’t open the glove box or trunk. The purpose of this key is to protect any valuables you want to keep in your trunk or glove box when you give your car to a valet. On some luxury cars, a valet key will start your vehicle, but it won’t allow the car to go over 35 mph.  Most valet keys do not have a battery in them, but they will usually have a computer chip like any master key. Since they have a computer chip, the process to replace your valet key will probably be the same as getting any of the other types of master keys replaced. You will need to go to a dealership or qualified locksmith.

aftermarket keyless entry remote - auto keys

Aftermarket keyless entry remote with manufacturers basic transponder key

An aftermarket key is one that is not the original from your manufacturer. If you have added a remote starter or a new alarm system in your vehicle, you may have an aftermarket key.  If you purchased a used car, or had a remote starter or an alarm system installed, you will not be able to take your aftermarket remote to the dealership for service. Places like Best Buy or an auto accessory store that installs these items is your best bet for help with an aftermarket remote.

Cost: If you simply need a new battery, batteries for auto keys or key remotes cost less than $5 and are very easy to change yourself. There are places, like Batteries Plus, that will change the battery for you at no charge when you purchase the battery at their store. There are some dealerships and auto service centers that will also charge you less than $5. If you decide to take your key or key remote into a place to get your battery changed and they try and charge you $30 or some other unreasonable amount, go somewhere else.

If you need to get your key replaced, it is much more expensive than replacing a battery. Since auto keys now contain computer chips in them to help prevent theft, you can no longer just take a key and have copies made for a few dollars. You will have to take it to a dealership or locksmith to have it cut and programmed. Valet keys may be a little bit cheaper than master keys since most don’t have the buttons to lock and unlock car doors. There are so many different types of manufacturers and models that it would be hard to name every price. Most modern auto keys are going to be anywhere from $150 – $600.

About The Author

Pedals and Pumps

PedalsandPumps provides direct, honest information about car maintenance and repair. We provide money and time saving tips for readers who want to maximize their dollar and simplify their auto owning experience.


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