Hyundai Key Fob Battery Replacement: Which Battery It Takes (CR2032) and How to Change It
Nearly every Hyundai key fob made since the mid-2000s takes a single CR2032 battery, whether it is a flip key, a separate remote or a push-button smart key. A few older remotes take a thinner CR2025, so read the code on the old cell before you buy. To open a smart key, slide the catch and remove the emergency key, then twist a flat tool in the slot it came from; on 2020-and-newer smart keys the back cover slides off instead. Fit the new battery the same way round, close the case and press lock to test. No reprogramming is needed.
Hyundai makes this job easier than most: the battery is almost always a CR2032, and the fobs are designed to be opened at home. The things that go wrong are small ones: prying at the wrong spot and marking the case, fitting the battery upside down, or trapping the rubber button pad when the case closes. This guide covers each style of Hyundai key, how to start the car when the fob is dead, and what to check if a new battery does not fix it.
Which battery your Hyundai key fob takes
| Key style | Typical FCC ID | Common on | Battery |
|---|---|---|---|
| Separate remote with a plain key (older cars) | OSLOKA-310T, PINHA-T038, OSLOKA-850T | Elantra 2007 to 2012, Sonata 2006 to 2010, Santa Fe 2007 to 2012, Accent, Tucson 2005 to 2009 | CR2032 (a few take CR2025) |
| Flip key (buttons on the key, blade folds out) | TQ8-RKE-3F04, TQ8-RKE-4F25, OSLOKA-950T, NYOSEKS-TF10ATX | Elantra 2011 on, Sonata 2011 to 2019 (keyed trims), Tucson 2010 on, Santa Fe 2013 on, Accent, Veloster, Kona, Venue | CR2032 |
| Smart key, 2010 to 2019 (push-button start) | SY5HMFNA04, SY5DMFNA04, TQ8-FOB-4F11, TQ8-FOB-4F07, SY5MDFNA433 | Sonata 2011 to 2019, Elantra 2011 to 2020, Santa Fe 2013 to 2018, Tucson 2016 to 2021, Genesis sedan, Azera, Veloster, Ioniq | CR2032 |
| Smart key, 2020 on (flat key with slide-off cover) | TQ8-FOB-4F27, TQ8-FOB-4F28, NYOMBEC5FOB2004, TQ8-FOB-4F26 | Sonata 2020 on, Palisade, Santa Fe 2019 on, Tucson 2022 on, Elantra 2021 on, Kona 2022 on, Ioniq 5 and 6, Santa Cruz | CR2032 |
A CR2025 looks identical to a CR2032 but is 0.7 mm thinner. If your old cell says CR2025, buy a CR2025; a CR2032 can stop the case closing and strain the contacts. The code on the flat + face of the old battery is the final word.
If you are curious, the first two digits of a coin cell code are the diameter in millimetres and the last two are the thickness in tenths of a millimetre. Our key fob battery size chart covers every common size.
What you need
- One new CR2032 (or the code on your old cell). Panasonic, Energizer, Duracell or Murata; Hyundai dealers sell the same cells in Hyundai packaging
- A small flat-blade screwdriver, a coin, or a plastic pry tool
- A clean surface with good light so the rubber button pad does not go missing
Avoid rechargeable LIR2032 cells. They are the same shape but a higher voltage than the fob is designed for.
Changing the battery in a Hyundai smart key (2010 to 2019)
This is the rounded fob with a hidden emergency key, used on push-button start models up to about 2019.
Press or slide the release on the side of the fob and pull the metal key out. You will use its tip in the next step.
Look into the slot the emergency key came out of. There is a notch for a flat tool. Put the key tip or a small flat screwdriver in it and twist. The two halves part. Do not pry at the outer seam; that is how the case gets chewed.
On most Hyundai smart keys the + side, with the code printed on it, faces up towards you once the back is off. Take a photo before you touch it.
Lever it up at the cut-out beside it with the key tip or a plastic tool and lift it out by the edge. Keep metal tools off the circuit board.
Hold it by the edge and press it in the same way round. It should sit flat under the retaining tab without rocking.
Snap the halves together, slide the emergency key back in until it clicks, and press lock and unlock. The LED flashes with each press when the battery is good.
Changing the battery in a 2020-and-newer Hyundai smart key
The flat key on the Sonata, Palisade, Tucson, Ioniq 5 and other recent models has a sliding back cover rather than a split case.
- Press the release button and pull out the emergency key.
- With the key removed, put a thumb on the back cover and push it towards the end where the key came out. On some models you first press a small tab in the key slot with the key tip, then slide the cover. It moves a few millimetres and lifts off.
- Lift the CR2032 out at the cut-out, noting which side faces up (usually the + side).
- Fit the new cell the same way round, slide the cover back until it clicks, and refit the emergency key.
Changing the battery in a Hyundai flip key
- Press the button to fold the blade out. Look along the seam of the plastic head for a small slot, usually on the side near the pivot or at the end opposite the blade.
- Put a flat screwdriver or coin in the slot and twist gently. The back cover comes away. A few older remotes have a small Phillips screw instead; remove it first.
- Note which way the battery faces, then lever it out at the cut-out beside it.
- Press in the new CR2032 the same way round, check the rubber button pad is seated flat, and snap the cover back on.
The immobilizer chip that lets the car start is sealed in the key head and does not use the battery. A flip key with a dead battery still turns the ignition and starts the engine.
CR2032 3V lithium coin battery
Nearly every Hyundai flip key and smart key takes a CR2032. Buy a name brand in a small multi-pack, check the date on the pack, and keep the spares in the glove box.
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Do you need to reprogram a Hyundai key after a battery change?
No. The pairing is stored in memory that does not need battery power, so the fob works as soon as the new cell is in. If the cluster showed Key battery low or Replace key battery, it clears after the next start or two. Programming is only needed for a key that is new to the car.
If the car still says the key is not detected
First, start the car. On any push-button Hyundai, hold the smart key against the Start button (buttons facing the button) and, with your foot on the brake, press the Start button with the fob itself. The car reads the chip in the key through the button and starts. The emergency key blade opens the driver’s door; on fobs with no visible keyhole, the lock cylinder is under a small cap on the handle that pops off with the key blade.
Then check, in this order:
- Battery size. A CR2025 in a CR2032 holder sits loose and makes patchy contact. Compare the new code with the old one.
- Battery upside down. No LED flash at all usually means the cell is reversed.
- Flattened contact. The spring contact can be pressed down while prying. Lift it gently with a plastic tool and wipe it with a dry cotton bud. See how to clean key fob battery contacts.
- A flat new battery. Unbranded multi-pack cells and cells that have sat for years can be dead in the packet. Try one from a fresh, dated pack.
- The car’s 12 V battery. If the car was also slow to crank, the key is not the problem. See can a bad car battery cause key fob problems.
- Damage inside the fob. A fob that has been dropped hard, through the wash or left on a hot dash can have a cracked solder joint. A locksmith can test whether it still transmits before you pay for a new key.
The full checklist is in Hyundai key fob not working and key fob not working after a battery replacement.
What it costs
Most Hyundai parts counters will fit a battery while you wait for the price of the cell plus a few dollars, and some do it free during a service visit. The larger figures only apply when the key itself has to be replaced, which a battery change almost never leads to.
How long the new battery will last
A flip key only transmits when you press a button, so its CR2032 normally lasts three years or more. A smart key listens for the car and answers every time you touch a handle, so expect one to two years from the same cell. Cold winters, leaving the fob within a few feet of the car overnight, and carrying it loose where items press the buttons all shorten that. See how long key fob batteries last for a sensible replacement schedule.
Safety: keep coin batteries away from children and pets
A swallowed coin cell can cause serious internal burns within hours. Keep spares and the old cell out of reach, and take old batteries to a drop-off point rather than household waste. If you think a child has swallowed a battery, go to the emergency room straight away and call the National Battery Ingestion Hotline at 1-800-498-8666, or Poison Help at 1-800-222-1222.
Frequently Asked Questions
Almost all Hyundai flip keys, remotes and smart keys take a CR2032. A few older remotes take a CR2025. Confirm with the code printed on the old battery.
Remove the emergency key, then twist a flat tool in the notch inside the slot it came from. On 2020-and-newer flat keys, remove the emergency key and slide the back cover off instead.
No. Hyundai keys keep their pairing without battery power. The fob works as soon as the new battery is in, and any key battery low message clears after the next start or two.
Hold the smart key against the Start button and, with your foot on the brake, press the button with the fob itself. Use the emergency key blade to open the driver’s door.
Not reliably. The CR2025 is thinner, so it sits loose in a CR2032 holder and gives patchy range. Use the code the fob was designed for.
Check that the new cell is the right size, the right way up, and from a fresh pack, and that the contact spring was not flattened. If the fob LED flashes but the car ignores it, use the backup start and have a locksmith test the fob.