Replace the Key Fob Battery

Last updated: June 5, 2026

If the remote on your Toyota Yaris Mk4 (XP210, 2020–present) has become weak — you have to stand close to lock or unlock, or a low-battery warning has appeared — the smart key’s coin cell needs replacing. The Yaris keyless key uses a CR2032 cell and the job takes a couple of minutes with a small screwdriver. This guide shows how.

What You Need

• One fresh CR2032 3 V lithium coin cell.
• A small flat-blade screwdriver (tape the tip to avoid marking the case).
• Clean, dry hands — skin oils shorten coin-cell life.

How to Replace the Yaris Key Battery

1. Slide out the mechanical (emergency) key: push and hold the small release knob and pull the metal key out of the fob.
2. Insert the screwdriver into the slot the key leaves and gently separate the two halves of the case (don’t use excessive force).
3. Lift out the old CR2032 cell — avoid touching the terminals with your fingers.
4. Fit the new cell with the positive (+) side facing up, as the old one sat.
5. Refit the battery cover, click the case halves back together, and slide the mechanical key back in.
6. Operate the remote — the LED should light, confirming it works.

Does It Need Programming?

No — replacing the coin cell does not affect the fob’s pairing, so the key keeps working immediately. Programming a brand-new or replacement key requires Toyota’s diagnostic equipment at a dealer or auto locksmith.

Frequently Asked Questions

What battery does the Yaris Mk4 key take?

A single CR2032 3 V lithium coin cell.

Will the car still start if the smart-key battery dies?

Yes. Hold the fob against the start button (Toyota marks the spot) to start using the backup transponder. The mechanical key in the fob unlocks the door.

Why shouldn’t I touch the battery terminals?

Skin oils leave a residue that increases contact resistance and shortens the new cell’s life. Handle it by the edge.

My remote still won’t work with a fresh cell — now what?

Re-open it and check the cell orientation and that the contacts are clean. If it’s still dead, the fob may have an internal fault and need replacing and programming by a dealer or locksmith.

To clear a service reminder after maintenance, see our Toyota Yaris service indicator reset guide. For warning lights, look up the code on autodtcs.com.