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Dead Key Fob Battery on a 2024 Acura MDX: How to Get In and Start the SUV

If your 2024 Acura MDX key fob battery is dead, the SUV may not unlock remotely and you may see “Keyless Access System Problem” or similar warnings. The good news: you can still get in using the hidden mechanical key and often still start the vehicle using the backup start procedure. Replacing the fob battery usually restores normal operation in minutes.

Understanding Your Situation

The coin-cell battery inside the Acura Smart Entry remote is weak or depleted, reducing the fob’s signal so the MDX can’t reliably detect it for unlock/lock or push-button start. Cold weather, infrequent use, and an aging battery can make the problem appear suddenly.

🚀 Immediate Steps to Take

  1. Use the hidden mechanical key to unlock the driver’s door: slide the release on the fob to remove the key, then insert it into the driver door key cylinder (typically behind a small cover on the handle) and turn to unlock.
  2. Try the backup start method: with the fob inside the cabin, press the brake and use the fob against/near the START/STOP button (or hold it very close) while pressing the button to allow the vehicle to read the transponder even with a weak battery.
  3. Replace the fob battery as soon as possible: open the fob case carefully, install a new coin-cell battery of the correct type (match the number printed on the old battery), and confirm lock/unlock and remote functions work.

Your Options

Replace the key fob battery yourself (DIY)

Cost: $3-$12 Time: Same day

Open the MDX key fob, remove the old coin-cell battery, and install a new one matching the battery type printed on the original. Reassemble the fob and test remote lock/unlock and starting.

âś“ Pros:
  • Fast and inexpensive
  • No programming needed for a battery change
  • Restores remote range and reliability
âś— Cons:
  • Risk of cracking the fob housing if pried incorrectly
  • Wrong battery type or upside-down installation can cause continued issues

Have a dealership replace the battery

Cost: $0-$30 Time: Same day

Bring the fob to an Acura dealer for battery replacement and a quick function check of the remote and Smart Entry operation.

âś“ Pros:
  • Professional handling reduces chance of damage
  • They can confirm the fob is working and check for related vehicle warnings
âś— Cons:
  • May require an appointment or waiting
  • Higher cost than DIY (unless provided as a courtesy)

Use a local locksmith or automotive shop

Cost: $20-$80 Time: Same day

A mobile locksmith or repair shop can replace the battery and verify the fob is transmitting properly. Useful if you’re stranded or can’t easily get to a dealer.

âś“ Pros:
  • Convenient, often mobile service
  • Can help confirm whether the issue is battery vs. a damaged fob
âś— Cons:
  • Cost varies widely by location and travel fees
  • Not all shops stock the correct battery or handle Acura fobs regularly

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

Cost: $250-$600 Time: 1-3 days

If a new battery doesn’t restore function, the fob may have internal damage (water intrusion, broken buttons, worn contacts). Replacement requires an OEM or compatible fob and programming to the vehicle.

âś“ Pros:
  • Restores full Smart Entry and remote features reliably
  • Addresses physical damage or internal failure
âś— Cons:
  • More expensive than a battery
  • Requires programming and proof of ownership

⚠️ What to Avoid

✕ Don’t force the fob case open with excessive pressure—use gentle prying and avoid metal tools that can gouge the housing or damage internal clips.

✕ Don’t touch the new coin-cell battery surfaces excessively—skin oils can reduce contact quality; handle by the edges when possible.

✕ Don’t assume the car battery is dead—if interior lights and dash power up normally but the remote doesn’t work, the fob battery is the likely cause.

Frequently Asked Questions

Can I still start my 2024 Acura MDX if the key fob battery is dead?

Often, yes. Use the backup start procedure: keep the fob in the cabin, press the brake, and press the START/STOP button while holding the fob very close to the button so the vehicle can read it even with a weak battery. If it still won’t start, the fob may be damaged or there may be another issue.

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

No. A battery replacement does not erase programming on Acura Smart Entry remotes. If the fob stops working after a new battery, double-check battery type, orientation, and that the fob housing is fully snapped together.

What battery does a 2024 Acura MDX key fob use?

It uses a coin-cell battery, but the exact type can vary by fob version. The most reliable method is to open the fob and match the number printed on the existing battery (for example, CR2032 is common in many fobs).

Why does my fob work only when I’m very close to the MDX?

Reduced range is a classic sign of a weakening coin-cell battery. Replace the battery first. If range is still poor, the fob may be damaged or there may be interference from other electronics.

⏱️ Urgency Note: Low to moderate urgency: you can usually unlock the door with the mechanical key and start using the backup method, but replace the battery soon to avoid being locked out or unable to start at an inconvenient time.

Related Information

Need Detailed Information?

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

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Last updated: 2026-01-04