Dead Key Fob Battery medium urgency

Dead Key Fob Battery? How to Start and Unlock a 2024 Hyundai Santa Fe (US)

If your 2024 Hyundai Santa Fe key fob suddenly won’t unlock the doors or allow push-button start, the fob battery may be dead. The good news: you can usually get in and start the vehicle using the backup methods built into the fob and the car.

Understanding Your Situation

The key fob uses a small coin-cell battery to power the remote buttons and the proximity signal for Smart Key features. When the battery voltage drops too low, the Santa Fe may not detect the fob reliably, so lock/unlock, remote start (if equipped), and push-button start recognition can fail or become intermittent.

🚀 Immediate Steps to Take

  1. Use the hidden mechanical key inside the fob to unlock the driver’s door (look for the release latch on the fob, remove the key, and use the door lock cylinder).
  2. Start the Santa Fe using the emergency Smart Key method: hold the fob close to the START/STOP button (or press the fob against the button area) and then press the brake and push START. This helps the vehicle read the fob even with a weak battery.
  3. Replace the key fob battery with the correct coin-cell (commonly CR2032 on many Hyundai smart keys, but confirm by opening your fob or checking your owner’s manual) and test lock/unlock and starting before you drive away.

Your Options

DIY key fob battery replacement (recommended first)

Cost: $3-$12 Time: Same day (10-20 minutes)

Open the fob case carefully, replace the coin-cell battery with the same type, and reassemble. No programming is typically required for a simple battery swap.

âś“ Pros:
  • Cheapest and fastest fix
  • Usually restores full Smart Key range immediately
âś— Cons:
  • Risk of cracking the fob housing if pried incorrectly
  • If the issue isn’t the battery, you may still need diagnosis

Battery replacement at a parts store or electronics counter

Cost: $5-$25 Time: Same day

Buy the correct coin-cell battery and ask staff to help install it (availability varies by store).

âś“ Pros:
  • Less chance of damaging the fob during opening
  • Quick if the battery is in stock
âś— Cons:
  • Not all stores will install batteries in key fobs
  • May still need to confirm the correct battery type

Dealer service (battery + quick system check)

Cost: $15-$60 Time: Same day / 1-3 days (depending on appointments)

A Hyundai dealer can replace the battery and confirm the vehicle is recognizing the fob properly, checking for related issues (e.g., weak fob, damaged fob, or vehicle-side antenna concerns).

âś“ Pros:
  • Professional handling and verification
  • Good option if warnings persist after a new battery
âś— Cons:
  • Higher cost than DIY
  • May require an appointment or wait time

Replace the key fob (if battery replacement doesn’t help)

Cost: $250-$600 Time: Same day / 1-7 days (parts availability)

If the fob is damaged (water intrusion, cracked circuit board, worn buttons) or still isn’t detected with a fresh battery, you may need a replacement fob and programming.

âś“ Pros:
  • Restores full functionality when the fob itself has failed
  • Can include a new emergency key blade cut to match
âś— Cons:
  • Most expensive option
  • Programming typically requires dealer-level tools or a capable automotive locksmith

⚠️ What to Avoid

✕ Don’t force the fob case open with a large screwdriver—use a small plastic pry tool if possible to avoid cracking the housing or damaging the seal.

✕ Don’t install the wrong battery type or flip polarity—match the battery model exactly and note the +/– orientation before removal.

✕ Don’t assume it’s the car battery immediately—if the vehicle starts normally once it detects the fob near the button, the issue is usually the fob battery, not the 12V system.

Frequently Asked Questions

How do I start my 2024 Hyundai Santa Fe if the key fob battery is dead?

Use the emergency Smart Key method: press the brake and hold the fob right next to the START/STOP button (or press it against the button area), then press START. This allows the vehicle to read the fob at very close range even if the fob battery is weak.

How do I unlock the door if the fob won’t work?

Remove the mechanical key from the fob using the release latch/slider, then unlock the driver’s door using the key cylinder. After you get in, you can use the emergency start method and replace the fob battery.

What battery does the 2024 Santa Fe key fob use?

Many Hyundai smart keys use a CR2032 coin-cell, but confirm by opening your specific fob or checking the owner’s manual because battery type can vary by fob design and trim.

Do I need to reprogram the key fob after replacing the battery?

Usually no. A battery swap typically does not erase programming. If the fob still doesn’t work after a new battery, the fob may be damaged or the vehicle may need diagnosis.

Why does the fob work sometimes and fail other times?

A weak coin-cell can cause intermittent range and detection issues, especially in cold weather. Replacing the battery often fixes inconsistent lock/unlock and “Key not detected” messages.

⏱️ Urgency Note: Low to moderate urgency: it’s usually safe to drive once you can start the vehicle, but replace the fob battery soon to avoid being locked out or unable to start at an inconvenient time. If you’re stuck in an unsafe location, use the mechanical key to enter and move to a safer place before troubleshooting.

Related Information

Need Detailed Information?

Get vehicle-specific key fob compatibility, part numbers, and a complete price comparison for your 2024 Hyundai Santa Fe.

View Santa Fe Key Fob Guide →

Last updated: 2026-01-04