Replace the Key Fob Battery

Reviewed by the Service Reset editor · Updated August 9, 2026 · How we verify
Quick referenceToolsNew CR1632 cell + flat screwdriverTime~5 minMethodReplace CR1632 coin cell — programming retained

These instructions apply to the Lexus IS Mk3 (XE30) 2013-2020.
For other models, please choose your vehicle here.

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.

Lexus IS Mk3 — the vehicle covered in this guide.
Lexus IS Mk3. Photo by Dinkun Chen via Wikimedia Commons, licensed CC BY-SA 4.0.

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:

  1. Push and hold the release knob and pull out the mechanical key.
  2. 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.)
  3. Lift out the old cell (don’t touch the terminals) and fit a new CR1632, positive side up.
  4. 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.

Independent guide — not affiliated with Lexus. Always follow your official service manual and safety precautions. Read our full disclaimer.

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