2021 Kia Optima (K5) Key Replacement

The 2021–2024 Optima (K5 since 2021) uses the same key setup, so everything on this page applies to those years too. The full picture is on the Kia Optima (K5 since 2021) key guide.

2021 Kia Optima (K5 since 2021): key facts

Key type: Smart / proximity key
Push-to-start: Yes
Transponder chip: 4A (NXP Hitag AES)
Programming: OBD
All keys lost: We can originate new keys on site

Renamed K5 (DL3 platform). Most trims: push-button start with the 4A Hitag-AES smart fob (CQOFD00790 / 95440-L3010). The base LX kept a turn-key ignition WITHOUT an immobilizer — the 2021-2022 K5 is in the Hyundai/Kia theft class list, and cars.com's 2021 trim rundown separately notes the base LX lacks push-button start and an engine immobilizer — and those cars need no transponder programming at all. Smart-key OBD programming may require a Kia PIN (dealer/KDealer or NASTF-credentialed source) depending on the tool.

What key does the 2021 Optima (K5) use?

For 2021 Kia renamed the Optima the K5 and moved it to the DL3 platform. Most trims are push-button start and use a smart proximity fob. The chip family is 4A, which is NXP Hitag AES, and the common fob is the CQOFD00790, part number 95440-L3010. Several independent parts references agree on that chip, so we treat it as verified.

In plain terms, the car checks for the fob electronically when you press the start button. A plain cut metal key will not start it. The fob also has to be paired to the car's computer, and that is done with programming equipment plugged into the OBD port under the dash. Nobody can do it with a key blank and a file.

Every one of these fobs also holds a mechanical backup blade. If the fob battery dies or the fob stops working, the blade still opens the driver's door. That blade matters more than people expect, and we come back to it below.

Spare key or all keys lost: what changes?

If you still have a working fob, making a duplicate is the simpler job. The original key is needed for duplication on this setup, so bring it with you or have it with the car. We cut or supply the blade, program the new fob to the car, and test that it starts the engine and locks and unlocks.

If every fob is gone, replacement is still possible. All keys lost can be handled on this car, but it takes more steps. We confirm the car's identity from the VIN and ownership paperwork, make a new fob and blade, and program it through the OBD port. Any fobs you find later should be re-registered or removed, so a lost one cannot keep working on the car.

Working fob in hand: duplicate, usually the lighter-cost route.
No working fob: all-keys-lost replacement, still doable, more involved.
Either way, expect to show proof that the car is yours.

The car says the key is not detected: is the fob dead?

The most common complaint on these cars is a dead fob battery. The dash reports that the key is not detected, the engine will not start, but the emergency blade still opens the door. In many cases that is a battery problem and not a lost key, and replacing the battery is far less work than programming a new fob.

If a fresh battery does not fix it, the cause may be a water-damaged or crushed fob. Fobs that went through the wash or got sat on in a back pocket often fail on the inside. At that point replacement and programming is the answer. We will tell you which one you are dealing with before we do anything more than the problem needs.

Locked out or need a locksmith now?

We answer around the clock, every day of the year.

Call (213) 577-1366

What affects the cost of a replacement fob?

Replacing a smart fob costs more than replacing an older bladed key, and that is simply the nature of the part. We do not quote numbers on a web page because the final figure depends on your situation, but here is what moves it:

Whether you have a working original (duplicate) or no keys at all.
Whether the car needs a Kia PIN code to accept a new smart key. This depends on the programming tool, and the code comes through the dealer or a credentialed source.
How many fobs you want made at one visit.
Whether the blade needs cutting as well as the fob programming.
Whether you come to our Westwood storefront or want a mobile van to come to the car.

The base LX and what we confirm by VIN

Not every 2021 Optima (K5) follows the smart-fob pattern. The base LX kept a turn-key ignition and has no engine immobilizer. Those cars need no transponder programming, so a key can be cut without pairing. The 2021-2022 K5 also appears on the Hyundai/Kia theft class list, which is worth knowing as an owner.

Trim and equipment can vary, and the PIN requirement depends on the tool used, so we check the VIN before we commit to a plan and confirm in person. If a particular car turns out to need something only a dealer can supply, we will say so up front and not guess.

Wilshire Lock & Key has been in business since 1987, with a storefront at 10740 Wilshire Blvd in Westwood and mobile vans. You deal with one company, with David overseeing the work, and not a dispatch middleman. For other model years, see the Kia Optima key guide or the wider Kia key overview. You can also browse all car key services or contact us with your VIN. Call (213) 577-1366 any time.

Frequently asked questions

Does the 2021 Kia Optima (K5) have a push-button start?

Most trims do, with a smart proximity fob. The base LX is the exception, with a turn-key ignition and no immobilizer.

Can you make a key if I lost all my fobs?

Yes, all keys lost is possible on this car. We verify ownership and the VIN, then make and program a new fob through the OBD port.

Do I need the original key to make a copy?

For duplication on this setup, yes, an original key is needed. If you do not have one, the job becomes an all-keys-lost replacement.

My Optima says the key is not detected. Do I need a new fob?

Not necessarily. A dead fob battery is the common cause, and the emergency blade will still open the door. If a new battery does not help, the fob may be water-damaged or crushed.

Will a Kia PIN be required?

It may be, depending on the programming tool. The PIN comes from the dealer or a credentialed source. We confirm by VIN before we start.

Does the base LX need programming?

No. The base LX has a turn-key ignition without an immobilizer, so no transponder programming is needed.

Can you come to my car?

Yes. We run mobile vans in addition to our Westwood storefront. Call (213) 577-1366, answered 24 hours a day.

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Reviewed by David, Owner & Lead Technician, Wilshire Lock & Key — in the locksmith trade since 1987.

Last updated 2026-10-11.