These instructions apply to the Toyota Prius Mk1 Prius+ (ZVW40) 2012-2016. For other models, please choose your vehicle here.
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If the Smart Key on your Toyota Prius+ (ZVW40, 2012–2016) has become weak — you have to be close to lock or unlock, or a “key battery low” message has appeared — the fob’s coin cell needs replacing. The Prius+ key uses a CR2032 cell and the job takes a couple of minutes. 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.
How to Replace the Prius+ Key Battery
- Slide out the mechanical (emergency) key: release the catch and pull the metal key from the fob.
- Insert the screwdriver into the slot the key leaves and gently separate the case halves (don’t use excessive force).
- Lift out the old CR2032 cell — avoid touching the terminals with your fingers.
- Fit the new cell with the positive (+) side facing up, as the old one sat.
- Click the case halves back together and slide the mechanical key back in.
- Test lock/unlock and Smart Entry from a normal distance.
Does It Need Programming?
No — replacing the coin cell does not affect the fob’s pairing, so the key keeps working immediately. A brand-new or replacement key must be ordered and programmed by Toyota with a diagnostic tool.
Frequently Asked Questions
What battery does the Prius+ key take?
A single CR2032 3 V lithium coin cell.
Will the car start if the key battery dies?
Yes. Hold the fob against the START/STOP button (Toyota marks the spot) and press to start using the backup transponder. The mechanical key in the fob unlocks the driver’s 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 key 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 by Toyota.
To clear a service reminder after maintenance, see our Toyota Prius+ service indicator reset guide. For warning lights, look up the code on autodtcs.com.
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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