These instructions apply to the Lexus IS Mk3 (XE30) 2013-2020. For other models, please choose your vehicle here.
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If the smart key on your Lexus IS (2013–2020) has lost its range or shows a low-key-battery message, the coin cell inside is almost certainly flat. It’s a quick swap — just check which key you have, as the IS key takes a CR1632 (not the CR2032 many cars use), and the card-style key takes a CR2412.
Battery First — Check Your Key Type
- Standard smart key (with a pull-out mechanical key) — CR1632.
- Card-style smart key — CR2412.
If the key is dead you can still start the car: hold it against the START button as you press it. The mechanical blade in the standard key unlocks the driver’s door.
Replacing the Cell
Standard smart key:
- Push and hold the release knob and pull out the mechanical key.
- Separate the two halves of the case with a small screwdriver at the seam. (Some keys are held by clips you discard and replace on reassembly.)
- Lift out the old cell (don’t touch the terminals) and fit a new CR1632, positive side up.
- Close the case and refit the mechanical key.
Card key: pull off the button-cell cover, fit a new CR2412 positive side up, and refit the cover.
Lost Key or Adding a Spare
A cell swap keeps the existing coding. A new key must be programmed by a Lexus dealer with diagnostic equipment — there’s no owner sequence on the IS.
If a Fresh Cell Doesn’t Help
- Confirm the cell type and orientation (CR1632 standard, CR2412 card, positive up).
- Hold the key to the START button to drive in the meantime.
- Still flagging? A smart-entry fault can store a code — look it up on autodtcs.com.
Frequently Asked Questions
What battery does the Lexus IS key use?
A CR1632 in the standard smart key, or a CR2412 in the card-style key — note it’s CR1632, not the more common CR2032.
Do I need to reprogram the key after the swap?
No — the coding is retained for a battery change.
Can I program a new IS key myself?
No — a new key must be coded by a Lexus dealer with a diagnostic tool.
The key is dead — how do I start the car?
Hold the key against the START button as you press it.
If the key flagged low after a battery disconnection, see our IS battery disconnect/reconnect guide.
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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