Replace the Key Fob Battery

Reviewed by the Service Reset editor · Updated August 22, 2026 · How we verify
Quick referenceToolsNew CR1620 cell + flat screwdriverTime~5 minMethodReplace CR1620 coin cell — programming retained

These instructions apply to the Mazda 3 Mk2 (BL) 2009-2016.
For other models, please choose your vehicle here.

If the remote on your Mazda 3 Mk2 (BL, 2009–2016) has become weak — you have to stand close to lock or unlock — the fob’s coin cell needs replacing. The Mazda 3 remote uses a CR1620 cell. This generation also lets you re-register a remote yourself without a dealer tool. This guide covers both.

Mazda 3 Mk2 — the vehicle covered in this guide.
Mazda 3 Mk2. Photo by RL GNZLZ from Chile via Wikimedia Commons, licensed CC BY-SA 2.0.

What You Need

  • One fresh CR1620 3 V lithium coin cell.
  • A small flat-blade screwdriver.

How to Replace the Battery

  1. Unclip the remote control unit from the main key — use a screwdriver at the marked arrow.
  2. Remove the key cover with the screwdriver.
  3. Lift out the old CR1620 cell.
  4. Fit the new cell with the positive (+) side facing down.
  5. Refit the cover and engage the remote unit back onto the main key.
  6. Check the remote locks and unlocks the car.

Re-registering a Remote Yourself

If the remote has lost its pairing (or you’re adding a spare — up to 3), the Mazda 3 can be put into programming mode without a tool:

  1. Remove the key, close all doors and the boot, then open the driver’s door.
  2. Within 24 seconds, insert the key and turn the ignition ON and OFF 3 times (leave the key in).
  3. Close and open the driver’s door 3 times — the door locks cycle to confirm programming mode.
  4. Press any button on the remote twice — the locks cycle to confirm it’s registered.
  5. Repeat for any other remotes, then close the door to exit.

Note: a brand-new transponder key (for starting) still needs a dealer to code the immobiliser.

Frequently Asked Questions

What battery does the Mazda 3 BL remote take?

A CR1620 3 V lithium coin cell, fitted positive-side-down.

Can I really program a remote without a dealer?

Yes — the ignition-cycle and door sequence above registers the remote’s button functions. It doesn’t program a new transponder for starting (that needs a dealer).

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, try re-registering with the sequence above; if that fails, the fob may have an internal fault.

For battery work that may also be needed, see our Mazda 3 battery disconnect/reconnect guide. For warning lights, look up the code on autodtcs.com.

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

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