Dead Key Fob Battery medium urgency

Dead Key Fob Battery on a 2023 Toyota Corolla (US): How to Unlock & Start Your Car

If your 2023 Toyota Corolla key fob suddenly won’t lock/unlock the doors or the car says the key isn’t detected, the most common cause is a dead fob battery. The good news: you can usually still get in and start the car, then replace the battery quickly.

Understanding Your Situation

The small coin-cell battery inside the Corolla’s smart key fob has run down, reducing the fob’s signal strength. Remote buttons may stop working first, then proximity features (Smart Key) may fail or become intermittent.

🚀 Immediate Steps to Take

  1. Unlock the driver’s door using the hidden mechanical key inside the fob (release the latch on the fob and pull the key out; insert it into the driver’s door key cylinder).
  2. Start the car using the emergency start method: hold the Toyota emblem side of the fob against the START/STOP button and press the brake, then press START/STOP (the car reads the transponder even with a weak/dead battery).
  3. Replace the coin-cell battery as soon as possible (commonly a CR2032 for Toyota smart keys, but confirm by checking the old battery marking or your owner’s manual) and test lock/unlock and key detection afterward.

Your Options

DIY battery replacement (most common fix)

Cost: $3-$10 Time: Same day

Open the smart key fob case, remove the old coin-cell battery, install a new one with the correct polarity, then reassemble and test all functions.

âś“ Pros:
  • Fast and inexpensive
  • Restores remote and Smart Key functions in most cases
âś— Cons:
  • Small parts can be easy to lose
  • Incorrect battery type/polarity can cause continued issues

Battery replacement at a dealer or locksmith

Cost: $0-$25 Time: Same day

A service advisor, parts counter, or locksmith replaces the fob battery and verifies operation. Helpful if you’re unsure how to open the fob without damage.

âś“ Pros:
  • Low effort and minimal risk of breaking the fob shell
  • Quick confirmation the issue is truly the battery
âś— Cons:
  • May require a trip during business hours
  • Some locations charge for labor or the battery

Diagnose other causes (if a new battery doesn’t fix it)

Cost: $0-$80 (diagnosis) / $200-$500+ (replacement key fob programmed) Time: Same day / 1-3 days

If the fob still won’t work after a known-good battery, the issue may be a damaged fob, water intrusion, a vehicle-side problem, or interference. A dealer or automotive locksmith can test the fob and vehicle receiver and advise whether repair or replacement is needed.

âś“ Pros:
  • Finds the real cause if it isn’t the battery
  • Avoids buying unnecessary parts
âś— Cons:
  • Replacement fobs and programming can be expensive
  • May require proof of ownership and an appointment

⚠️ What to Avoid

âś• Forcing the fob case open with excessive prying (can crack the shell or damage the internal board); use gentle pressure at the intended seam/slot.

âś• Installing the battery upside down or using the wrong size (always match the battery code printed on the old cell and confirm polarity).

✕ Assuming the car is immobilized—your Corolla can typically be started by holding the fob to the START/STOP button even with a dead fob battery.

Frequently Asked Questions

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

Yes, in most cases. Use the emergency start method: press the brake and hold the fob against the START/STOP button (Toyota emblem side toward the button), then press START/STOP. The vehicle can read the key’s transponder even if the fob battery is depleted.

What battery does a 2023 Toyota Corolla key fob use?

Many Toyota smart key fobs use a CR2032 coin-cell, but variations exist. The most reliable method is to open the fob and read the battery code printed on the old battery, or confirm in your owner’s manual/parts department before buying.

Will replacing the key fob battery erase programming or require reprogramming?

No. Replacing the coin-cell battery does not typically erase the key’s programming. After replacement, the remote and Smart Key functions should work normally if the battery was the issue.

Why did the alarm go off when I unlocked the door with the mechanical key?

Some vehicles may trigger an alarm when the door is unlocked mechanically. Starting the car with the recognized smart key (including the emergency start method) typically stops the alarm. If it continues, consult your owner’s manual for the correct disarm procedure.

⏱️ Urgency Note: Low to moderate urgency: you can usually still unlock the door with the mechanical key and start the Corolla using the emergency start method, but replace the fob battery soon to avoid being stranded if the mechanical key access is blocked (ice/damage) or the fob becomes unreliable.

Related Information

Need Detailed Information?

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

View Corolla Key Fob Guide →

Last updated: 2026-01-04