Bought a Used Car With Only One Key? What to Do in the First Week

Why Do So Many Used Cars Come With Just One Key?

Because spares go missing long before cars get sold, and nobody along the way is paid to replace them.

New cars normally leave the factory with more than one key. The owner's manual for an early-2000s Honda Accord, for example, lists two master keys plus a valet key, and the 2024 CR-V's manual still lists a key number tag among the items the car comes with, for ordering replacements. Then years of ownership happen:

• The spare was lost long ago and nobody noticed, because the everyday key kept working.
• It stayed behind — in a kitchen drawer, with an ex, with a kid who took it to college.
• The car was traded in with one key, and every owner after that inherited the gap.
• A new fob costs real money, so from the seller's side, buying one right before selling rarely feels worth it.

Across the Phoenix metro, used cars change hands at franchise and independent lots, in private sales from Chandler to Peoria, at auctions, and through online retailers that deliver to your door — and any of those routes can end with one key in your hand. We're not going to quote a figure for how often it happens; numbers float around online and we haven't seen one we'd stand behind. What we can say: it's common, it's rarely a sign of anything wrong with the car, and it's easy to fix while you still have one working key.

What Kind of Key Did the Car Come With?

Check before you buy anything — you may have more key than you think, or less. Look at three things on the ring and in the glove box, work out which type of key it is, and ask the seller one question.

1. A blade hidden inside the fob

Most remote fobs and smart keys hide a metal blade. Press or slide the release and it comes out — Honda's 2024 CR-V manual calls it the built-in key and describes it as the way to unlock the doors when the remote's battery is weak. Find it now, and find the keyhole on the driver's door too — on some cars it hides under a small cap on the handle. Our key fob troubleshooting guide walks through it.

What the blade is not: a spare. It's part of the same key. On a push-to-start car it won't start the engine by itself, and if the fob is lost, the blade goes with it.

2. A valet key

Some cars — mostly older ones with a turn-key ignition — came with a valet key, often with a different-colored head. In that early-2000s Accord manual, the valet key works only in the ignition and the door locks, so a parking attendant can drive the car but can't open the trunk or glove box. If you got a master key and a working valet key, you actually have two keys that start the car. Many newer cars simply don't have one.

3. The paperwork in the glove box

Look for the owner's manual and a small key number tag or plate. The manual's keys section tells you what the car shipped with; the tag carries the key's number, and Honda's manual says you'll need it to buy a replacement key. If it isn't there, ask the seller — it's often in the same drawer as the missing key.

4. Which type of key it is

Plain metal, transponder chip, remote-head key or fob, or push-to-start smart key — the type sets the price of a spare. Our car key cost guide shows how to tell them apart, and the locksmith glossary has short definitions if a term throws you. Older cars with a plain metal key and no chip are the easy case: a hardware-store copy that turns the ignition is a working spare, and you don't need us for it.

One more used-car tell: if the key you got is worn — sticky in the door, or fighting you in the ignition — mention it when you call. Where the key code is available, a new key can be cut to the original spec instead of copying the wear.

What Happens If You Lose the Only Key?

It stops being a copy job and becomes an all-keys-lost job: more work, a higher starting price, and a car that stays put until a key is made.

With a working key in hand, a spare is a copy — the tech cuts the blade to match and registers the new key with the car's immobilizer alongside the one you already have. With no key at all, there's nothing to copy: the key has to be made from scratch, from the door lock or the key code, and then programmed to the car. The full walkthrough is in Lost All Your Car Keys? Here's Exactly What to Do.

These are starting prices, not flat quotes. The real cost of a car key depends on the exact vehicle and runs from about $200 to $1,200+, so the tech confirms the exact price on-site, before any work begins. A $59 service call brings the tech and equipment out to lock that price; it's credited to the job if you go ahead. After 8PM, every service carries a flat $60 night charge. Everything else is on our price list, and the service itself is on the car key programming page.

Why two keys beat one — beyond the price

• Inconvenienced versus stranded. Lose the only key in a parking lot in July and the car stays exactly where it is until a key is made there or it's towed. With a spare at home, it's a phone call to whoever can bring it.
• Some cars let owners add a key themselves — with two. Ford's 2020 Transit owner's manual, for example, describes an owner procedure for adding a key that starts with two keys already programmed to the vehicle. With one key, that option isn't on the table.
• The only key takes all the wear. It goes everywhere the car goes, hot parked cars included, and Honda's manual warns against leaving keys in direct sunlight or high heat — which describes most parked cars in a Valley summer. More on that in why key fobs fail in Arizona heat.

Could Someone Else Still Have a Key to Your Car?

Possibly — and you usually can't tell by looking. A key that's registered to the car starts it no matter whose pocket it's in, and a change of ownership doesn't clear that list. The fix is to have keys you don't have erased when your spare is programmed.

Cars with an immobilizer keep a list of the key codes they'll accept. Ford describes its SecuriLock system as an engine immobilizer that won't let the engine start without a coded key programmed to that vehicle, and the 2020 Transit manual linked above allows up to eight coded keys on a single vehicle. So a car that was sold with one key may still recognize others.

Who might have one? Not necessarily anyone with bad intentions: a previous owner's spouse or teenager, a spare left with a shop that serviced the car, a key on a lot's key board, the second key the seller couldn't find this week and finds next month. That's the point — you don't know.

What happens in the programming session

On most makes, while your spare is being programmed, we can erase all previously registered keys so only the ones in your hand work — then register your existing key and the new spare. On some vehicles the programming tool can also show how many keys the car currently recognizes. The exact procedure varies by make and model, and not every car allows it; text us the year, make and model (or the VIN) and we'll tell you what's possible for yours before anyone drives out.

Three things to get right:

1. Bring every key you have, including a valet key. Erasing clears the list; any key that isn't there has to be registered again later.
2. Wait for a promised key. If the seller says they'll mail the second key, either wait for it or accept that once old keys are erased, that key won't start the car until it's registered again.
3. Know the limit. Erasing stops an old key from starting the engine. The metal blade of an old key may still turn the door lock, and whether old remotes stop working depends on the car. If one particular key worries you, tell us on the call.

What Do You Need to Bring to Get a Spare Made?

Your photo ID and the registration or title, the car itself, and every key you have. Any good locksmith will ask for proof the car is yours — it protects you, because it means keys don't get made for cars that aren't the caller's.

• Have the VIN ready. It's at the bottom of the windshield on the driver's side, on the sticker in the driver's door jamb, and on your registration and insurance card. Text it to (623) 200-4499 and we'll reply with your starting price.
• Just bought it in a private sale? If the registration isn't in your name yet, bring the title that was signed over to you along with your ID, and tell us on the call where your paperwork stands so we can confirm before anyone drives out. If all you have so far is a bill of sale, say so on the call too.
• Financed it? The lender usually holds the title, so your registration is the document to bring. If the permanent one hasn't arrived yet, tell us on the call what the dealer gave you.
• Every key you have — the working key, a valet key, anything the seller handed over — so each one can be registered again if old keys are erased.

What Should You Ask About Keys Before You Sign?

Ask how many keys come with the car, and if a second key is promised, get that promise written into the deal. If you're still shopping, this is the cheapest point to solve the problem.

1. Ask early: how many keys come with it, and what kind? Ask the dealer, the private seller, or check the online listing's details or condition report — and ask if the key count isn't there.
2. Try every key. Start the car with each one, press every button, and try the blade in the driver's door. A key that unlocks the doors but won't start the car isn't a second key.
3. Get promises onto the paperwork. If the seller or dealer says they'll find, order or mail a second key, have it written on the purchase documents — many dealers use a "We Owe" or due-bill form for exactly this kind of promise. A spoken promise is easy for both sides to forget.
4. Price the gap. If only one key comes with the car, a spare is a real cost — our starting prices are $149, $199 or $279 depending on key type — and it's fair to bring that up while you're still talking price.
5. Private sale? Ask the seller to look for the second key, the owner's manual and the key number tag before you meet.

This is practical buying advice, not legal advice. The paperwork you sign is what counts, so read it before you sign it.

When Is Someone Else the Right Call?

Sometimes the dealer, sometimes nobody at all (if the seller finds the second key, just make sure it starts the car) — and when it's the dealer, we'll tell you on the phone.

• Late-model European cars — BMW, Mercedes, Audi — often need dealer programming. We say so on the phone, for free, instead of sending a tech out to find out.
• If an open recall or factory repair involves the key or the immobilizer, let the dealer handle that work.
• Already bought a fob online? We program only the keys and fobs we supply ourselves, so we're not the right call for programming that one.

Your First-Week Plan for a New-to-You Car

1. Find the hidden blade in your fob and the keyhole on the driver's door, and try the blade in the lock once so you know it works before you need it.
2. Check the glove box for the owner's manual and a key number tag, and message the seller or dealer about a second key.
3. Check for open recalls by VIN on NHTSA's recall lookup. Enter the 17-character VIN; if a safety recall hasn't been repaired, the automaker's dealer fixes it at no charge.
4. Get the spare made this week, while you still have a key to copy. Bring every key you have and ask to have keys you don't have erased — possible on most makes.
5. Test every key: start the car, lock, unlock, trunk, and the blade in the door.
6. Store the spare away from the car — not in the glove box, not on the same ring. At home, where someone can bring it to you.
7. Keep the fob out of the sun in a parked car when you can; Arizona summers are hard on key electronics and batteries.

Frequently Asked Questions

Is it normal for a used car to come with only one key?

Yes — common enough that it's worth checking before you assume otherwise. New cars normally leave the factory with more than one key, but spares get lost, stay behind with a family member, or never make it to the trade-in, and sellers rarely pay to replace an expensive fob right before selling. It isn't a sign anything is wrong with the car. It just means your next step is a spare.

Does the metal blade hidden in my key fob count as a spare?

No. The blade inside most fobs and smart keys is part of the same key. It opens the driver's door when the fob battery dies, but on a push-to-start car it won't start the engine by itself, and if you lose the fob, the blade goes with it. A spare is a second, separately programmed key that starts the car on its own.

Does a valet key count as a second key?

On cars that have one, mostly yes. A valet key is usually a coded key that opens the doors and starts the car but won't open the trunk or glove box, so it will get you home if the main key goes missing. It's also a key someone else could use, so bring it along when a spare is programmed. Many newer cars don't come with a valet key at all.

How can I tell if someone else still has a key to my car?

Usually you can't from the outside. A key registered to the car starts it no matter whose pocket it's in, and a change of ownership doesn't clear that list. The practical fix is to have keys you don't have erased when your spare is programmed — on most makes that happens in the same session. Bring every key you own so each one is registered again.

What's the difference between a spare key and an all-keys-lost job?

A spare is made while you still have a working key: the tech copies it and registers the new key alongside it. All keys lost means there's nothing to copy, so the key is made from scratch and then programmed to the car. With TrustKey, spares start from $149 for a transponder key, $199 for a remote fob and $279 for a smart key; all keys lost starts from $349. The exact price is confirmed on-site before work begins.

Should I ask for a second key before I buy a used car?

Yes. Ask how many keys come with the car and what type they are, then start the car with each one before you sign. If the seller or dealer promises to find or order a second key, get that promise written into the purchase paperwork instead of leaving it as a handshake. If only one key comes with the car, count the cost of a spare as part of the price you're paying.