Replace Key Battery medium urgency

2024 Nissan Altima Dead Key Fob Battery: How to Unlock & Start Your Car

If your 2024 Nissan Altima key fob suddenly won’t unlock the doors or the car says “Key Not Detected,” the fob battery is often the cause. The good news: you can still get in and usually still start the car using the built-in backup methods.

Understanding Your Situation

The coin-cell battery inside the Intelligent Key fob has discharged, reducing or stopping the fob’s signal. This can prevent remote lock/unlock and may trigger “No Key Detected” messages, especially if you’re not holding the fob close to the start button.

🚀 Immediate Steps to Take

  1. Unlock the driver’s door with the hidden mechanical key (release the key from the fob and use the door’s key cylinder—often behind a small cover on the handle).
  2. To start the Altima, hold the Nissan logo side of the fob against/very close to the START/STOP button and press the button while pressing the brake (this allows the car to read the fob even with a weak/dead battery).
  3. Replace the fob battery as soon as possible (commonly a CR2032 coin cell for Nissan Intelligent Keys—verify the exact type printed on your old battery before buying).

Your Options

DIY battery replacement (coin cell)

Cost: $3-$12 Time: Same day

Open the key fob case, swap in a new coin-cell battery matching the original (type is printed on the old battery), and reassemble the fob. Test lock/unlock and starting afterward.

âś“ Pros:
  • Lowest cost
  • Usually restores full function immediately
âś— Cons:
  • Risk of damaging the fob if pried incorrectly
  • May not fix the issue if the problem is the fob itself or the vehicle’s receiver

Battery replacement at an auto parts store or locksmith

Cost: $10-$35 Time: Same day

A technician replaces the battery and can often check basic fob output and inspect for corrosion or damage.

âś“ Pros:
  • Quick and convenient
  • Less chance of breaking the fob housing
âś— Cons:
  • Costs more than DIY
  • Quality depends on the battery brand used

Dealer service (battery + key/fob inspection)

Cost: $20-$60 (battery/service); $250-$550+ if a new fob is needed Time: Same day / 1-3 days (if ordering parts)

A Nissan dealer replaces the battery and can diagnose if the issue is a failing fob, a programming problem, or a vehicle-side issue. They can also quote replacement fobs if needed.

âś“ Pros:
  • Best option for diagnosing persistent “Key Not Detected” issues
  • Access to OEM parts and factory diagnostic tools
âś— Cons:
  • Highest cost
  • May require an appointment

⚠️ What to Avoid

✕ Don’t force the fob case open with excessive prying—use gentle pressure and the correct seam to avoid cracking the housing or damaging internal clips.

✕ Don’t install the new coin cell upside down—match the polarity (+/-) exactly as the old battery was installed.

✕ Don’t assume it’s only the battery if problems continue after replacement—water intrusion, a damaged fob, or interference can cause similar symptoms.

⚠️ Common Mistakes to Avoid

  • Using wrong battery type
  • Damaging case during opening
  • Not resetting after replacement
  • Buying expensive batteries

Frequently Asked Questions

Can I still start my 2024 Nissan Altima if the key fob battery is dead?

Yes in most cases. Unlock the door with the hidden mechanical key, then hold the fob against/very close to the START/STOP button and press the button while pressing the brake. This lets the car read the fob even if the battery is weak or dead.

What battery does a 2024 Nissan Altima key fob use?

Many Nissan Intelligent Key fobs use a CR2032 coin-cell battery, but you should confirm by checking the battery type printed on the old battery inside your fob or referencing your owner’s manual for your exact fob part number.

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

Typically no. Replacing the coin-cell battery usually does not erase programming. If the fob still won’t work after a correct battery replacement, the fob may be damaged or the vehicle may need diagnosis.

Why does the car say “Key Not Detected” even when the fob is in the cabin?

A weak/dead fob battery is common, but interference (phones, other keys), a damaged fob, or issues with the vehicle’s antennas can also cause it. Try starting with the fob held against the start button; if it persists after a new battery, have it inspected.

⏱️ Urgency Note: Low immediate safety risk, but replace the battery soon—if the fob battery is fully dead and you don’t know the mechanical key procedure, you can get locked out or be unable to start the car when you need it.

Related Information

Need Detailed Information?

Get vehicle-specific key fob compatibility, part numbers, and a complete price comparison for your 2024 Nissan Altima.

View Altima Key Fob Guide →

Last updated: 2026-01-04