These instructions apply to the Toyota Yaris Cross Mk1 (XP21) 2021-Present. For other models, please choose your vehicle here.
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A weak smart key is the usual reason a Toyota Yaris Cross (XP21, 2021–present) stops locking from a distance or shows a “key battery low” message. The fob takes one coin cell and you can change it in a couple of minutes.
Battery You Need
The Yaris Cross smart key uses a CR2032 3 V coin cell. Check the cell you remove and match it.
How to Replace the Key Battery
- Push and hold the release and slide out the mechanical key.
- Insert a small screwdriver into the slot (tape the tip to avoid marks) and separate the two cases.
- Lift out the old CR2032, noting the orientation — don’t touch the terminals.
- Fit the new cell with the positive (+) side facing up.
- Clip the cases back together and slide the mechanical key home.
Lock and unlock from a few metres to confirm; the fob LED should flash when a button is pressed.
If It Still Won’t Work
- Start the car anyway — touch the smart key to the start button as you press it; the car reads the transponder directly.
- Lock/unlock manually with the mechanical key.
Frequently Asked Questions
What battery does the Toyota Yaris Cross key take?
A single CR2032 3 V coin cell, positive side up.
Do I need to reprogram the key after changing the battery?
No — only adding a new key needs dealer programming.
How do I open the Yaris Cross smart key?
Slide out the mechanical key, then separate the cases with a taped screwdriver.
My key still won’t start the car — what now?
Hold the key against the start button as you press it.
For a no-start with a warning light, check the code on autodtcs.com. See also our Yaris Cross battery guide if the car is dead.
Disclaimer: The information on this page is provided for general guidance only. Always follow your official service manual and safety precautions when working on your vehicle. We are not responsible for errors, omissions, or any damage resulting from the use of this information.
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