Only one key? What a missing spare does to your car's value

Yes, a missing spare key usually lowers what a buyer will offer, because whoever buys your car either pays to have a replacement made and programmed before resale or accepts less when they sell it on. Replace it first only if a written quote comes in under the difference it makes to your offer and the new key can be ready before the inspection. Otherwise, tell the buyer up front and let them price it in.

Why does a missing spare key lower the price?

A second key is part of what the next owner expects to get. A dealer buys your car to resell it, and the person who buys it next will ask about the spare just as you’re asking now.

On a car built in 2021 or later, replacing a key is rarely a quick job at a hardware counter. Most keys now contain a chip that talks to the car’s immobiliser, and many are proximity keys that unlock the doors and start the car without leaving your pocket. A new one usually has to be ordered for that car, cut if it has a metal blade, and programmed so the car recognises it. That costs money and time, and buyers account for both.

There’s also a security question. If the missing key was lost away from home, someone else may have it. A careful buyer will ask where it went, because a key that could still open the car is a different problem from a key sitting in a drawer at your parents’ place.

A buyer’s allowance for a missing key generally reflects what they expect a replacement to cost them and how long it will take to arrive. That’s why there’s no single answer to “how much is a missing key worth”. It depends on the car and the key.

What kind of key does your car have?

The type of key decides how hard it is to replace, so check yours before you do anything else. Your owner’s manual names it, and the table below covers the common types on late-model cars.

If your car has push-button start, it usually has a proximity smart key. Many smart keys also hide a small metal blade inside the fob for opening the door when the battery is flat. That blade belongs with the key at handover, so check it’s still there.

What if your car uses a key card or a phone as the key?

Tesla is the best-known example. Tesla’s Model 3 owner’s manual describes a phone key that works through the Tesla app, key cards, and key fobs, which Tesla sells separately as an accessory. The phone key is the everyday key, and a card is the backup when your phone is flat, lost or not with you. If you bought a fob, it goes with the car too.

What matters at sale time is the cards. Go by what you were handed at delivery, then check the key list on the touchscreen, which shows every phone key, key card and fob that can access the car. If a card has gone missing, Tesla sells replacement key cards, and the manual explains that a new card is paired at the car by scanning a key that’s already paired. Delete the lost card from the key list while you’re there. Do all this before the inspection if you can, because a buyer will count the cards the way they count keys on any other car.

The phone key is the part sellers forget. Tesla’s manual sets out two steps: a factory reset from the touchscreen, then removing the car from your Tesla account in the app. The order matters, because the manual says you can’t do the reset once the car has been removed from your account. Leave both steps until handover day, once the money has cleared, because until then you may still need your phone key to move or charge the car. Our guide to selling a used Tesla Model 3 or Model Y covers the rest of the handover.

If another brand’s app lets you use your phone as a key, the same principle applies. The physical keys or cards go with the car, and your phone’s access is removed, following the maker’s instructions, before it leaves.

Should you replace the missing key or just disclose it?

Disclose it either way. The real question is whether to also replace it, and this is the rule. Replace the key before you sell only if all three of these are true:

1. You have a written quote, and it’s less than the difference the key makes to your offer.
2. The key can be supplied and programmed before the inspection.
3. The new key will do everything the original did: lock, unlock, keyless entry if the car has it, and start the car.

If any of those fails, disclose the missing key and let the buyer price it.

To find that difference, ask. When the valuer asks how many keys you have, say one, then ask whether the offer would change if you supplied a second. It’s a fair question on any valuation call, and the answer is the number your quote has to beat.

Why not replace it by default? Because if the buyer was only going to allow less than your quote, you’ve paid more for the key than it was worth to the sale. A rushed order can also push back your sale date. Use this table to find your situation.

Where do you get a replacement: dealer or locksmith?

There are two main options, and it’s worth asking both for a quote.

Expect either one to ask for proof that the car is yours, so have your photo ID and rego papers ready. Ask both whether the missing key can be removed from the car’s memory when the new one is programmed. That matters if you don’t know where the old key ended up.

Key prices vary widely by make, model and key type. Figures you see quoted online for someone else’s car won’t tell you much about yours, so get your quotes in writing with programming included. Then you can compare them with the difference the key makes to your offer.

Check your car insurance before paying. Some comprehensive policies include replacing keys and locks, others offer it only as an optional extra, and cover is often limited to keys that were stolen rather than lost. Your product disclosure statement (PDS) sets out the limits, conditions and any excess.

Are prestige and European car keys harder to replace?

Often, yes. On many European prestige models, a replacement key is ordered through the brand’s dealer network against the car’s VIN and coded to that car. Depending on the brand and model, a locksmith may not be able to supply one, and the order can take a while to arrive.

That changes the decision in two ways. First, ask the dealer for the lead time before you commit to a sale date, because a key that arrives after the inspection doesn’t help you. Second, buyers of prestige cars tend to expect the complete set: owner’s manuals, service history and both keys. Disclose a missing key at the start rather than letting the inspector find it.

If you own one of these cars, our page on selling a prestige car covers what else buyers of European and luxury models look at.

What should you tell the valuer about your keys?

Say how many keys you have, what type they are and whether each one works. Getting this right on the call means the first offer already allows for it, so there’s nothing new for the inspection to find. Our guides to what happens on a car valuation call and why an offer can drop after inspection explain why accuracy on the phone protects your price.

Before the call, run through this key check:

• Count every key, key card and fob, including any in a drawer, a second car or a family member’s house.
• Test each key: lock, unlock, open the boot and start the car.
• If the car has keyless entry, walk up with each key in your pocket and check the doors respond.
• Replace a flat fob battery and test again. The owner’s manual shows how.
• Check the emergency blade is inside each smart key.
• Note whether any key is aftermarket rather than genuine.
• If you’ve ordered a replacement, write down when it’s due and who is supplying it.

Then tell the valuer exactly what you found. “Two keys, both genuine, both working” is a fine answer. So is “one key, the spare was lost last year and I don’t know where it is”. The second one just needs to be said early.

What happens to the keys when the car is sold?

Every key goes with the car: both keys or key cards, any valet key, any spare fob and any locking wheel-nut key. Take your house keys and garage remote off the ring first, and remove toll tags and parking passes from the car.

Keys change hands last, after payment. When you sell to us, the car and keys are collected only after you confirm the funds have cleared in your account. If you can’t be there on the day, key drop-off can be arranged, and our guide to car collection and key drop-off explains how that works.

Selling your car with one key

A missing spare isn’t a reason to put off selling. It’s a cost that gets priced in, and you decide whether you pay it or the buyer does. Look for the spare first, get a quote if it’s really gone, and tell the buyer up front either way.

If your car is 2021 or newer with 100,000 km or less, you can get a free valuation from Sell Your Car Australia. Tell us how many keys you have on the call, so the genuine offer you get from a licensed dealer reflects the car as it is. If you accept, we pay a deposit, often the same day, then inspect the car at a time and place that suits you. The balance goes into your bank account, and we collect the car, anywhere in Australia, only after you confirm the funds have cleared. No fees come out of the offer.

If your car is older or has more kilometres, send it through anyway and we’ll tell you straight away if we can help. You can also call 1800 73 55 73.