These instructions apply to the BMW 1 Series Mk3 (F40) 2019-Present. For other models, please choose your vehicle here.
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If the remote on your BMW 1 Series Mk3 (F40, 2019–present) is getting weak — short range, fussy Comfort Access, or a “key battery low” message — the coin cell needs renewing. The F40 key takes a CR2032 and opens with the emergency blade hidden inside.
What You’ll Need
- A fresh CR2032 3 V lithium coin cell.
- The emergency key blade that slides out of the fob.
How to Replace the F40 Key Battery
- Slide out the emergency key blade — push the small catch and pull the blade out.
- With the blade removed, slide/lever the cover off the back of the fob (the blade slot is the opening point).
- Lift out the old CR2032, noting which way up it sits.
- Fit the new cell the same way, by the edges.
- Click the cover back on and slide the blade home.
- Test lock/unlock and Comfort Access from a normal distance.
Does It Need Programming?
No — the swap doesn’t affect the key’s pairing, so it works straight away. A lost or extra key can only be ordered and coded by a BMW dealer.
If It Still Won’t Respond
Re-open the fob, check the cell orientation and clean the contacts. If Comfort Access is slow, hold the key against the start button / marked spot to start, then it re-syncs.
Frequently Asked Questions
What battery does the 1 Series F40 key take?
A single CR2032 3 V lithium coin cell.
Will the car start with a flat key battery?
Yes — hold the key against the start button (or marked spot) to start on the backup transponder; the emergency blade unlocks the driver’s door.
Which way up does the cell go?
Match the orientation of the cell you removed.
Can I program a spare key myself?
No — BMW key coding needs the dealer system. Only the battery swap is DIY.
To clear a service reminder after maintenance, see our 1 Series F40 service reset guide. For warning lights, look up the code on autodtcs.com.
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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