2021 Acura NSX Key Replacement

2021 NSX key specs

The hybrid NSX starts with a push button and uses a smart key that stays in your pocket. Parts catalogs list a four-button fob for 2017-2022 cars carrying FCC ID KR5V2X, the same ID used on the 2018-2020 TLX, but the car was built in small numbers at Acura's Performance Manufacturing Center in Ohio and we have not confirmed which fobs and programming routes work on it. Like other Acura smart keys, the fob contains a mechanical emergency key for the driver's door, which matters if the fob battery runs down while the car sits.

What's specific to the 2021 NSX

The 2021 Acura NSX is the fifth of 6 model years in the NSX Second generation (NC1) (2017–2022), so it shares its key system with the rest of that run, which makes replacement parts easy to source. A 2021 Acura NSX is about 5 years old now. Original fob batteries are near the end of their life at this age, so weak range or a "key not detected" message is often a battery before it is a failed fob. Cars this age are often on their second owner, which is when a single remaining key and a request for a spare tend to show up.

Smart-key cars like the 2021 NSX can be targeted with relay attacks that extend the fob's signal from inside your home, so keep fobs away from exterior walls or in a signal-blocking pouch, and have any missing fob erased from the car.

Key options for the 2021 Acura NSX

• Smart proximity key (push-to-start). Making a new smart key is mostly a programming job. The fob has to match the vehicle's FCC ID, frequency and chip, and then the keyless system must be told to accept it, normally through the OBD-II port. Depending on the platform, that can mean entering a PIN, waiting through a timed security procedure, or on some newer vehicles, using manufacturer online access. When every key is lost, certain models need a module removed and read on the bench. For your Acura NSX Second generation (NC1), we'll tell you which of those applies, and if a step is dealer-only, you'll hear it before we drive out. The emergency blade hidden inside the fob is cut by code during the same visit.

How the Acura immobilizer works on the NSX

Acura fitted an immobilizer to essentially every car it sold here from 2000 on, and the type of chip tells you a lot about how a replacement key gets made. Through the early 2000s, the TL, CL, RL, MDX, RSX, NSX and 2000-2001 Integra used a Megamos 13 fixed-code transponder inside a conventional key, with keyless entry handled by a separate remote. The 2004 TL and TSX introduced Philips ID46 (Hitag 2) crypto chips, which later moved into flip keys on the MDX, RDX, TL and TSX. The 2005 RL brought Acura's Keyless Access smart key, and by the late 2010s nearly every Acura used push-button start with a Philips ID47 (Hitag 3) smart fob. The newest designs, such as the 2022-and-later MDX and RDX, the 2023 Integra and the ADX, use Honda's latest smart key generation, while the electric 2024 ZDX uses a GM-designed system. In every case the engine computer checks the chip before it lets the engine run, so a key that is only cut will turn the ignition without starting the car. A flashing key symbol on the dash usually means the car didn't recognize the chip.

• Parts catalogs list a KR5V2X fob for the 2017-2022 NSX, but a matching fob still has to be registered to this low-volume hybrid, which is why we send programming to the dealer.
• The 2022 NSX Type S was the final model year for this generation.
• Long storage drains fob batteries, so a car that has sat for months may need a fresh fob battery before it will start.

Getting a 2021 NSX key from the dealer

Programming a second-generation NSX key is normally done by an Acura dealer with Honda's diagnostic equipment, because we have not confirmed aftermarket programmer coverage for this hybrid and a fob that is cut and registered incorrectly can cost you a second visit. What we can do is open the car if you're locked out, cut the emergency blade, and help you line up the dealer appointment with the right ownership paperwork.

Treat replacement NSX smart keys as a dealer job. We can still open the car, cut the emergency blade and help coordinate the order.

How we help when the key must come from Acura

Losing every key to an Acura is usually fixable where the car sits, but the path depends on the year. For cars with Megamos 13 or ID46 chips, roughly 2000 to 2013 including the flip-key models, we cut a key to your locks by code or by decoding a lock, then program it to the immobilizer through the OBD-II port. Most push-button models from about 2009 to 2020 follow the same pattern with a new smart fob, though low-volume cars like the RL, RLX and first ZDX can take extra steps. The newest platforms, such as the 2022-and-later MDX and RDX, the current Integra, the ADX and the 2021-2025 TLX, depend on current tool coverage, while the hybrid NSX and electric ZDX are dealer jobs. Before anything is cut, we check your photo ID against the registration or title.

1. Get you back into the car. If the car is locked, we open it on site without damage, so you can reach the registration, the VIN plate and anything you need inside.
2. Line up the dealer order. We help you gather what the Acura dealer will ask for: the VIN, current registration or title, and photo ID in the owner's name. That avoids a second trip.
3. Keep the car where it is if possible. Ask the dealer whether the key can be programmed with the car in place or whether it needs to be towed in. Some brands deliver a pre-coded key; others must program it at the vehicle.
4. Plan for a spare. Once you have a working key, order a second one. Losing the only key on a dealer-only system is the slowest and most expensive situation to recover from.

Why the 2021 NSX needs a dealer key

Some keys can't be made outside the factory network, and the 2021 NSX is one of them. Acura generates the key data on its own servers and ties it to the car's VIN, so a new key is either pre-coded before it ships or programmed at the vehicle with an online session that only authorized dealer equipment can open. Aftermarket tools that handle older Acura models can't complete that handshake on this generation, at least not reliably today. That is a security feature: it is the reason relay and key-cloning thefts are harder on cars like this.

What to bring to the dealer

Bring the vehicle registration or title in your name, a matching government photo ID, and the VIN (on the lower driver's side of the windshield and on the door-jamb label). If the car is financed or leased, the dealer may also ask for the lender's paperwork, so call ahead and ask exactly what they need. If any key still works, bring it; adding a key is usually faster than replacing every key.

While you wait for the new key

Waiting on a factory key can take anywhere from the same day to a week or more, depending on stock. In the meantime, avoid buying a used key online; on dealer-only systems a used key almost never programs to a different car. If you're locked out of the car or need something from inside it, call us; that part is quick and doesn't depend on the dealer.

What affects the dealer's price for an NSX key

Dealer key pricing depends on the key type (a smart key costs more than a basic remote key), whether the car needs to be at the dealership for programming, the dealer's programming or labor charge, and whether a tow is involved because no working key remains. Ask for the total, parts plus programming plus any tow, before you agree, and ask whether ordering two keys at once lowers the per-key cost.

Avoid doing this twice

Once you have a working key for your 2021 NSX, order a second one while the car's information is already on file. On dealer-only systems, adding a key while one still works is simpler, faster and cheaper than replacing every key after a loss. Keep the spare somewhere you can reach quickly, not in the car, and note where you stored it.

NSX key battery

If a new replacement doesn't bring the fob back, the battery wasn't the problem. Common culprits include a battery holder whose solder joints have cracked from drops, contacts corroded by moisture, worn rubber button pads that no longer reach the circuit, or a board damaged by water. We can test whether the fob is transmitting at all and inspect the board closely. Sometimes a new shell or a resoldered holder solves it; sometimes the fob has to be replaced and programmed. Meanwhile, the car can usually still be started with the fob held at the backup spot described in the owner's manual.

Common Acura key problems

• No-start after a key is dropped or run through the wash. A damaged chip can leave the key turning the ignition, or the fob locking doors, while the engine refuses to start. Testing the transponder tells us whether the key needs replacing.
• Seized driver's door lock cylinders on smart key cars. The emergency blade almost never gets used, so the cylinder can corrode and refuse to turn the day the fob dies. Try your blade in the door lock every few months.
• Lost remotes on models with separate fobs. On the early TL, CL, RL, MDX, RSX and first-generation TSX, the chip lives in the key, so a missing remote only affects keyless entry and can be replaced on its own.
• Weak smart key batteries. Most Acura smart fobs from 2009 on take a CR2032 coin cell. With a dying battery, holding the fob against the ENGINE START/STOP button usually lets the car read its chip and start anyway.
• Four-button spares on remote-start cars. Some 2014 and later Acuras shipped with a five-button fob that includes remote engine start. A four-button replacement will drive the car but won't start it remotely, so count your buttons before ordering.

Tips from a mobile locksmith

• On any vehicle with a turn-key ignition, keep the key ring light. A heavy cluster of keys, tools and charms swings with every bump and slowly wears the ignition wafers and the key itself. When the key starts to stick or needs a wiggle to turn, deal with it early, before it stops turning entirely.
• Learn your car's dead-fob start method now, in the driveway, rather than in a dark parking lot later. Depending on the make, you hold the fob against the start button or place it in a marked pocket in the console. Also find the hidden keyhole on the driver's door handle and practice using the emergency blade.
• Never hide a spare key or fob on the outside of the car. Magnetic boxes in wheel wells and under bumpers are the first places a thief checks, and with a proximity fob, a hidden key can let anyone open the doors and drive away. Keep the spare at home or with someone you trust.

Proof of ownership

Before we cut or program a key for any vehicle, we verify that you have the right to it. Please have two things ready: the current registration or the title, and a government-issued photo ID with a matching name. We also check that the VIN on those documents matches the VIN plate on the dashboard. If the registration is locked inside the car, that's fine; we open the vehicle first, check the paperwork in the glove box, and only then make the key. If something doesn't line up, we stop and sort it out before any key is made.

Need a 2021 Acura NSX key?

Call Julian's Locksmith at (951) 903-3193 if you're locked out of a 2021 Acura NSX or need help preparing a dealer key order. We'll tell you plainly what we can do on site and what has to go through Acura.