These instructions apply to the Mazda CX-30 Mk1 (DM) 2019-Present. For other models, please choose your vehicle here.
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A weak key is the usual reason a Mazda CX-30 (DM, 2019–present) stops locking from a distance or asks you to hold the fob to the start button. The CX-30 key takes a single CR2032.
Battery You Need
A single CR2032 3 V coin cell — the standard Mazda smart-key battery.
How to Replace the Key Battery
- Slide the catch and pull out the metal auxiliary key.
- Use a small screwdriver in the slot (tape the tip) to split the fob halves.
- Lift out the old CR2032, noting which way up it sits.
- Fit the new cell the same way up, avoiding the flat faces.
- Click the halves together and refit the auxiliary key.
Lock and unlock from a few metres to confirm.
If It Still Won’t Work
- Start the car anyway — hold the fob against the start button as you press; the car reads the transponder directly.
- Lock manually with the auxiliary key in the driver’s door (behind a small cap).
Frequently Asked Questions
What battery does the Mazda CX-30 key take?
A single CR2032 3 V coin cell.
Do I need to reprogram the key after changing the battery?
No — it pairs again as soon as power is restored.
How do I open the CX-30 key?
Pull out the metal auxiliary key, then split the fob with a small taped screwdriver.
My key still won’t start the car — what now?
Hold the fob against the start button as you press it.
For a no-start with a warning light, check the code on autodtcs.com. See also our CX-30 battery guide if the car is dead.
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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