Start the Car With a Dead Key Fob Battery

Last updated: June 10, 2026

If the remote on your BMW X1 (F48, 2015–2022) has gone silent – no unlock, a key-symbol warning in the cluster, or a dead Comfort Access – the coin cell inside the fob has almost certainly run flat. The F48 dropped the old dashboard key slot, so the trick that works on older 5 Series does not apply here. Instead, you unlock with the hidden blade and start the engine by holding the fob against a reader built into the steering column. Both steps are quick once you know where to look.

Unlock the door with the emergency key blade

With no battery, the remote will not lock or unlock the car, so the metal blade hidden in the fob is your way in.

1. Find the release catch at the base of the fob, slide it, and pull the metal emergency blade out of the housing.
2. Go to the driver’s door. The X1’s lock barrel is concealed – there is a small slot on the underside of the door handle rather than a visible keyhole.
3. Insert the blade into that slot and lever the trim cap off the end of the handle to expose the lock cylinder.
4. Turn the blade in the cylinder to unlock the driver’s door, then refit the cap once you are inside.

Unlocking mechanically can trip the alarm; it cancels as soon as the car detects a valid key in the cabin.

Start the engine by holding the fob to the steering column

The F48 reads the fob’s transponder through a ring antenna in the steering-column surround.

1. Sit in the driver’s seat, close the door, and press the brake pedal.
2. Look on the steering-column trim for a small embossed key symbol – it is usually on the right-hand side of the surround.
3. Hold the fob with its flat back pressed firmly against that symbol, making solid contact with the plastic.
4. Keeping the fob in place and the brake down, press the Start/Stop button. The car energises the chip and starts.
5. If nothing happens, reposition the fob slightly – pressing a different face or edge against the symbol helps the antenna find the coil.

Why the blade opens the door but does not start the engine

Only the fob’s remote-control features rely on the coin cell. Engine authorisation comes from a passive transponder chip that needs no battery; the steering-column antenna powers it inductively and reads its security code to release the immobiliser. The blade is purely mechanical – it moves the door lock but carries no code, which is why it can never start the car on its own.

Replace the fob battery (CR2032)

Fit a fresh cell as soon as you can to restore normal keyless use.

1. Remove the emergency blade; the gap it leaves is where you split the case.
2. Gently prise the two halves of the housing apart along the seam until the back cover releases.
3. Lift out the old CR2032 coin cell, noting its orientation, and press the new one in the same way.
4. Snap the case shut, refit the blade, and test the remote by locking and unlocking the X1.

Some sealed and rechargeable BMW fobs are not meant to be opened – if your F48 fob has no obvious seam or release catch, have it serviced rather than forcing it.

Frequently Asked Questions

Does the X1 F48 have a key slot like older BMWs? No. The F48 uses the steering-column reader instead, so there is no dashboard slot to push the fob into – hold it against the key symbol on the column.

Where exactly is the key symbol on the column? On the plastic surround around the steering column, generally to the right. It is a small embossed outline of a key; once you have used it once you will find it instantly next time.

The alarm sounded when I unlocked with the blade – is that normal? Yes. Mechanical entry bypasses the remote, so the alarm arms briefly until the immobiliser reads your key inside the car.

I held the fob to the column and it still will not start – why? First reposition the fob and try again. If the dashboard is dim or the car will not crank at all, the fault is more likely the X1’s own 12 V battery than the fob.

What battery does the F48 fob use? A CR2032 3 V lithium coin cell. Handle it by the edges to avoid shortening its life.

If a dashboard warning light appeared during the episode, you can decode it on our sister site autodtcs.com.