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2023 Toyota Highlander Dead Key Fob Battery: Get In, Start, and Replace It Fast

A dead key fob battery on a 2023 Toyota Highlander can stop remote lock/unlock and may prevent push-button start from detecting the fob. The good news: you can still unlock the door with the hidden mechanical key and start the vehicle using Toyota’s backup start method. Then replace the fob battery to restore normal operation.

Understanding Your Situation

The coin-cell battery inside the Highlander smart key fob has discharged, so the fob’s radio signal is too weak (or absent) for the vehicle to detect it at normal range. The vehicle’s backup methods still work because they rely on very close-range detection and/or the mechanical key blade.

🚀 Immediate Steps to Take

  1. Unlock the driver’s door with the hidden mechanical key: slide the release on the fob to pull out the key blade, then use the key cylinder on the driver’s door handle (remove the small cover if equipped).
  2. Start the Highlander using the backup method: hold the Toyota emblem side of the fob directly against the START/STOP button, then press the brake and press START/STOP (keep the fob touching the button until it starts).
  3. Replace the fob battery as soon as possible (commonly a CR2032 coin-cell for Toyota smart keys, but confirm the exact type printed on your old battery or in the owner’s manual) and test lock/unlock and starting range.

Your Options

DIY key fob battery replacement (recommended first step)

Cost: $3-$12 Time: Same day (5-15 minutes)

Open the smart key fob case, remove the old coin-cell battery, install a new battery of the same type with correct polarity, then snap the case back together and test all functions.

âś“ Pros:
  • Lowest cost and fastest fix
  • Restores normal range for lock/unlock and push-button start detection
âś— Cons:
  • You must confirm the correct battery type (do not guess)
  • Risk of damaging the fob case or seals if pried incorrectly

Battery replacement at a dealership service department

Cost: $10-$30 Time: Same day

A Toyota dealer replaces the battery and may perform a quick function check of the smart key.

âś“ Pros:
  • Professional installation with minimal chance of damage
  • Convenient if you’re already at the dealer
âś— Cons:
  • Higher cost than DIY
  • May require an appointment or waiting

Battery replacement at an auto parts store or local locksmith

Cost: $5-$25 Time: Same day

Many auto parts stores and locksmiths can replace a key fob battery and help confirm the correct battery type.

âś“ Pros:
  • Usually quick and affordable
  • Help confirming battery type and proper installation
âś— Cons:
  • Service availability varies by location
  • Not all shops will handle smart keys or may not stock the exact battery

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

Cost: $250-$600 Time: Same day to 1-3 days

If the fob still won’t work after a new battery, the fob may be damaged (water intrusion, cracked board, worn buttons) and may need replacement and programming to the vehicle.

âś“ Pros:
  • Resolves issues caused by internal fob failure
  • New housing/buttons and reliable operation
âś— Cons:
  • Most expensive option
  • Programming typically requires dealer or capable automotive locksmith

⚠️ What to Avoid

✕ Don’t force the fob case open with a large screwdriver or knife—this can crack the housing, damage the circuit board, or compromise water resistance.

✕ Don’t install the wrong battery size or flip polarity; it may not work and can bend contacts.

✕ Don’t assume the car battery is dead just because the fob won’t unlock—try the mechanical key and backup start method first.

Frequently Asked Questions

What battery does a 2023 Toyota Highlander key fob use?

Most 2023 Toyota Highlander smart keys use a CR2032 coin-cell, but you should confirm by checking the battery marking on the old battery or the owner’s manual for your exact key fob type.

Can I start my 2023 Highlander if the key fob battery is dead?

Yes. Unlock the door with the hidden mechanical key if needed, then hold the fob against the START/STOP button and press the brake while pressing START/STOP. This allows the vehicle to detect the fob at close range and start.

Will a dead fob battery trigger a warning message?

Often, yes. You may see a “Key Battery Low” or similar alert before it dies completely, and you may notice reduced range for lock/unlock.

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

Usually no. Replacing the coin-cell battery should not erase programming; normal operation should return immediately after installation.

Why does the car unlock with the key but the alarm goes off?

If you unlock with the mechanical key while the system is armed, the alarm may sound until the vehicle recognizes a valid smart key. Use the backup start method (fob to START/STOP) to authenticate and stop the alarm.

⏱️ Urgency Note: Low safety risk but potentially high inconvenience: replace the fob battery soon to avoid being locked out or stranded. If you’re traveling, carry a spare coin-cell and know where the mechanical key slot/cylinder is located on the driver’s door.

Related Information

Need Detailed Information?

Get vehicle-specific key fob compatibility, part numbers, and a complete price comparison for your 2023 Toyota Highlander.

View Highlander Key Fob Guide →

Last updated: 2026-01-04