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2024 Toyota Highlander Key Fob Not Working: Quick Fixes, Backup Start & Repair Options

If your 2024 Toyota Highlander key fob suddenly won’t lock/unlock or the vehicle won’t detect it for push-button start, the cause is usually a weak fob battery, interference, or a communication issue. The good news: Toyota provides a built-in backup method to unlock and start the Highlander even with a failing fob. Use the steps below to regain access safely and decide the best repair path.

Understanding Your Situation

The vehicle and key fob communicate using a low-power radio signal for remote functions and a proximity signal for Smart Key (keyless entry/start). When the fob battery is weak, the signal is blocked by interference, or the fob/vehicle has a fault, the Highlander may not respond to button presses or may display a “Key Not Detected” message.

🚀 Immediate Steps to Take

  1. Try the backup unlock/start: Use the mechanical key inside the fob to unlock the driver door, then hold the fob directly against the START/STOP button and press the brake + START to start the vehicle (this uses the fob’s passive transponder even if the battery is weak).
  2. Replace the key fob battery with a fresh name-brand coin cell (commonly CR2032 on many Toyota fobs, but confirm the exact battery type printed on your old battery or in your owner’s manual). After replacement, test lock/unlock and keyless entry.
  3. Rule out simple causes: Move the fob away from other electronics/metal objects, try your spare fob, and try a different location (parking garages and dense RF areas can cause interference). If neither fob works, the issue may be vehicle-side (12V battery, antenna/receiver, or system fault).

Your Options

Replace the key fob battery (DIY)

Cost: $3-$10 Time: Same day

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

âś“ Pros:
  • Fast and inexpensive
  • Often fixes weak-signal and intermittent detection issues
âś— Cons:
  • Won’t help if the fob is damaged or the vehicle has a receiver/12V issue
  • Incorrect battery type/poor contact can cause continued problems

Use the built-in backup start method (get moving now)

Cost: $0 Time: Immediate

Unlock with the mechanical key and start by holding the fob against the START/STOP button while pressing the brake and START. This bypasses the need for a strong fob battery for starting.

âś“ Pros:
  • Works even with a dead/weak fob battery (in many cases)
  • Lets you drive to a safe place or service location
âś— Cons:
  • Doesn’t fix remote lock/unlock range issues
  • If the fob is not recognized at all (damaged/unprogrammed), it may not work

Test/replace the vehicle 12V battery (if symptoms point to vehicle-side issue)

Cost: $150-$350 Time: Same day

Have the 12V battery tested (low voltage can cause smart key and body electronics glitches). Replace if weak, and ensure terminals are clean and tight.

âś“ Pros:
  • Fixes multiple odd electrical symptoms at once
  • Common cause if both fobs act up or the vehicle behaves inconsistently
âś— Cons:
  • Not the fix if only one fob is failing
  • Costlier than a fob battery

Repair or replace a damaged key fob (shell/buttons/water damage)

Cost: $40-$120 (shell repair) or $250-$600 (replace & program) Time: Same day / 1-3 days

If the fob was dropped, got wet, or buttons are worn, a locksmith or dealer can inspect it. Sometimes a new shell and transfer of the internal board helps; other times the fob must be replaced and programmed.

âś“ Pros:
  • Restores reliable operation if the fob is physically failing
  • Can be quicker than waiting for intermittent issues to worsen
âś— Cons:
  • Replacement requires correct fob type and programming
  • Aftermarket fobs vary in quality and compatibility

Dealer diagnosis for Smart Key/receiver or software faults

Cost: $150-$250 (diagnosis) + repairs Time: Same day / 1-3 days

A Toyota dealer can scan for body control and smart key system codes, verify antennas/receivers, check for service bulletins, and confirm fob registration status.

âś“ Pros:
  • Most accurate troubleshooting for vehicle-side faults
  • OEM parts and procedures
âś— Cons:
  • Higher cost than DIY
  • Appointment availability may delay repair

Mobile automotive locksmith (fob replacement/programming)

Cost: $180-$450 Time: Same day

A qualified locksmith can supply a compatible fob, cut the emergency key if needed, and program it on-site. Best for lost/damaged fobs or when you’re stranded.

âś“ Pros:
  • Convenient on-site help
  • Often less expensive than dealer replacement
âś— Cons:
  • Quality/compatibility varies—verify reviews and warranty
  • Some situations still require dealer support (module faults or restricted programming scenarios)

⚠️ What to Avoid

✕ Avoid repeatedly pressing the START button without using the backup method—if the fob battery is weak, it may never be detected until you hold it to the button.

âś• Avoid forcing the fob case open with metal tools that can crack the housing or damage the circuit board; use a plastic pry tool and follow the seam.

✕ Avoid buying the cheapest “universal” or mismatched fob online—incorrect FCC ID/part compatibility can prevent programming and waste time/money.

⚠️ Common Mistakes to Avoid

  • Assuming key is broken
  • Not checking battery first
  • Calling tow truck immediately
  • Replacing when reprogramming needed

Frequently Asked Questions

How do I start my 2024 Toyota Highlander if the key fob battery is dead?

Use the mechanical key to unlock the driver door, then hold the fob directly against the START/STOP button and press the brake and START. The vehicle can often read the fob’s passive transponder even with a weak/dead fob battery.

What battery does a 2024 Toyota Highlander key fob use?

Many Toyota smart key fobs use a CR2032 coin cell, but it can vary by fob version/trim. Confirm by checking the battery marking inside your fob or the owner’s manual before buying a replacement.

My Highlander says “Key Not Detected.” Is it always the fob battery?

No. A weak fob battery is common, but interference, a damaged fob, or a vehicle-side issue (including a weak 12V battery or smart key system fault) can also cause “Key Not Detected.” Try your spare fob and the backup start method to narrow it down.

If my remote lock/unlock doesn’t work, will the car still start?

Often yes. Remote buttons can fail from a weak battery while the proximity/passive function still works at close range. Use the backup start method by holding the fob to the START/STOP button if needed.

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

Usually no. A battery replacement typically does not erase programming. If the fob still doesn’t work after a correct battery install, the issue may be physical damage, incorrect battery contact/orientation, or a vehicle-side problem.

⏱️ Urgency Note: If you’re locked out, stranded, or the vehicle won’t start and you’re in an unsafe location, use the mechanical key and backup start method first, then move to a safe area. If you suspect theft/tampering or you’ve lost a fob, contact a dealer or trusted locksmith promptly to disable missing keys and protect the vehicle.

Related Information

Need Detailed Information?

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

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Last updated: 2026-01-04