These instructions apply to the Mazda CX-5 Mk1 (KE) 2012-2017.
For other models, please choose your vehicle here.
If the remote on your Mazda CX-5 Mk1 (KE, 2012–2017) has become weak — you have to stand close to lock or unlock, or a “key battery low” message has appeared — the fob’s coin cell needs replacing. The CX-5 uses a single CR2025 cell and the job takes a couple of minutes with a small screwdriver. This guide shows how, including the easy-to-miss O-ring.
What You Need
- One fresh CR2025 3 V lithium coin cell.
- A small flat-blade screwdriver (tape the tip to avoid marking the case).
- Clean, dry hands — skin oils shorten coin-cell life.
How to Replace the CX-5 Key Battery
- Slide out the emergency key blade: push and hold the small release knob on the fob and pull the metal key out.
- With the blade removed, insert the screwdriver into the slot it leaves and gently twist to separate the two halves of the case.
- Pull out the button-cell cover and lift out the old CR2025 cell.
- Fit the new cell with the positive (+) side facing up, matching how the old one sat.
- Check the rubber O-ring seal around the case edge is not twisted or displaced — it keeps moisture out, so seat it correctly.
- Click the two halves back together and slide the emergency key blade back in until it locks.
Test It
Lock and unlock the car from a normal distance. If the keyless start now reads the fob reliably and the low-battery message has gone, you are done. The new cell typically lasts a couple of years.
Does It Need Programming?
No — replacing the coin cell does not affect the fob’s pairing. The transponder and remote coding stay in place, so the key keeps working immediately. Programming is only needed for a brand-new or replacement key, which requires Mazda’s diagnostic tool (M-MDS) at a dealer or auto locksmith.
Frequently Asked Questions
What battery does the CX-5 Mk1 key take?
A single CR2025 3 V lithium coin cell. A CR2032 is slightly thicker and may strain the case — stick to the CR2025.
Will the car still start if the fob battery dies completely?
Yes. With keyless start, hold the fob against the start button (Mazda marks the spot) to start using the backup transponder. The emergency blade in the fob unlocks the door.
Why does the O-ring matter?
It seals the fob against moisture. If it’s pinched or left out, damp can get in and corrode the contacts — so check it sits flat before clicking the case shut.
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, the fob may have an internal fault and need replacing and programming by a dealer or locksmith.
To clear a service reminder after maintenance, see our Mazda CX-5 service indicator reset 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.