Start the Car With a Dead Key Fob Battery

Last updated: June 12, 2026

The Lancia Ypsilon (846, 2011–2024) — the third-generation supermini built on the Fiat 500 platform — uses a conventional remote key with a turn-key ignition barrel on the steering column. A dead fob battery is therefore a minor nuisance rather than a breakdown: the flat coin cell only stops the remote lock and unlock buttons. The metal blade and the immobiliser chip in the key still work, so you unlock the door and start the engine exactly as normal. This guide covers both, and how to fit a fresh cell.

Starting the Ypsilon With a Dead Fob

The Ypsilon has a key barrel, so a flat fob does not stop you driving:

1. Unlock the driver’s door with the metal blade (steps below) and get in.
2. Insert the same key into the ignition barrel on the steering column.
3. Press the clutch (manual) or brake (automated manual) and turn the key to crank the engine.
4. The engine starts normally — the immobiliser reads the transponder in the key head, which needs no battery.

The only thing a dead fob costs you is remote central locking. The car drives exactly as before.

Unlocking the Door With the Emergency Blade

With a flat battery the remote buttons go silent, so use the blade.

1. Press the release button on the fob to pop out (or fold out) the metal key blade.
2. Go to the driver’s door — the lock barrel is in or just behind the handle.
3. Insert the blade and turn to unlock.
4. This can set off the alarm; turning the ignition on with the recognised key clears it.

The Immobiliser Still Reads the Key

The Ypsilon’s immobiliser uses a passive transponder in the key, separate from the remote radio. When you turn the key, an antenna ring around the barrel energises that chip and reads its code to release the engine. Because the antenna powers the chip, a totally flat fob never prevents the engine starting — it only kills the remote locking.

Replacing the Key Fob Battery

The Lancia Ypsilon remote uses a single CR2032 3V lithium coin cell.

1. Press the release and remove the metal blade.
2. Lever off the logo cap, then undo the tiny screw and separate the two halves of the fob.
3. Lift out the old CR2032 and fit the new one with the “+” side facing the same way.
4. Reassemble the fob, refit the screw and cap, and reinsert the blade.
5. Press a button next to the car to confirm remote locking works again.

Frequently Asked Questions

Will a dead fob stop my Lancia Ypsilon starting? No. The Ypsilon uses a turn-key ignition, so it starts as normal — you only lose remote locking.

Which battery does the Ypsilon key take? A CR2032 3V lithium coin cell.

My Ypsilon cranks but won’t fire after the fob died — why? A flat fob can’t cause that on a turn-key car. Suspect the 12V battery, fuel or the immobiliser, not the coin cell.

Is the door keyhole hidden on the Ypsilon? No — the driver’s door has a visible barrel in or behind the handle.

Can I keep driving on just the blade? Yes. The Ypsilon is fully drivable on the blade; replace the CR2032 only when you want remote central locking back.

If a warning light stayed on after a flat fob or weak 12V battery, you can look up exactly what the code means on our sister site autodtcs.com.