These instructions apply to the Volkswagen Up Mk1 (AA) 2011-2023.
For other models, please choose your vehicle here.
When the remote on your Volkswagen up! (2011–2023) only locks the car from arm’s length, flashes weakly, or stops responding altogether, the coin cell inside the folding key has almost certainly gone flat. The up! — the city car VW built alongside the near-identical SEAT Mii and Škoda Citigo — shipped with two very different keys depending on trim: a folding “flip” remote with lock and unlock buttons on the mid and high-spec cars, and a plain button-less mechanical key on the entry-level “take up!”. Only the flip remote has a battery. Here is how to tell which you have, the exact cell it takes, how to open it without snapping the case, and why a replacement key is the one job you can’t finish at home.
How to Tell the Fob Battery Is Dying
- Shrinking range. You have to stand right next to the up! — or almost touch the fob to the door — before it locks or unlocks. This is the first and clearest sign.
- The button LED dims or stops flashing. The little indicator light on the fob normally blinks each time you press a button; once the cell is weak it goes faint or dies, which confirms the fault is in the key rather than the car.
- Only one press in several registers. Intermittent response — worse first thing on a cold morning — is a near-flat lithium cell struggling to deliver the brief surge the transmitter needs.
- The blade still works fine. If the key turns the barrel and starts the car normally but the buttons don’t, that points squarely at the fob battery, not the immobiliser.
A coin cell in an up! remote typically lasts two to four years. If yours is around that age and showing any of the above, fit a fresh cell before suspecting anything more serious.
The Battery You Need
The up! folding remote takes a single CR2032 — a 3-volt lithium coin cell, 20 mm across and 3.2 mm thick, the most common fob battery made and sold in any supermarket, hardware shop or petrol station. Buy a good branded cell rather than a bargain multipack; cheap cells sag under the transmitter’s brief current draw and can give poor range even when factory-fresh. If your up! came with the button-less “take up!” key, there is nothing to replace — that key is purely mechanical and holds no battery.
Method 1 — Folding “Flip” Remote (mid and high trims)
- Press the release button so the metal blade springs out, then fold the blade back in and hold it closed — the fob is far easier to grip and open with the blade tucked away.
- Turn the fob over and find the fine seam running around the edge where the two plastic halves meet, near the base of the blade hinge.
- Wrap the tip of a small flat screwdriver in a strip of tape to avoid scratching the case, slip it into the seam and twist gently to split the two halves apart. Work slowly around the joint rather than forcing one spot.
- Lift out the old CR2032. Note which way it sat before you remove it — the printed “+” face and which contact it rests against — and drop the new cell in the same orientation. Handle it by the edge; finger grease on the flat faces harms contact.
- Line the two halves up so the seam and button openings match exactly, press them together until they click shut, and test every button.
⚠️ Copy the orientation of the cell you took out. VW’s flip keys are fussy about which way the coin cell faces, and published guidance for VW remotes is inconsistent on whether the “+” points up or down — so don’t rely on a rule of thumb. Photograph or simply remember how the old cell sat and match it; a cell fitted the wrong way round simply won’t power the fob.
Method 2 — Button-less “take up!” Key (entry model)
The base up! was sold with manual central locking and a plain key that has no buttons and no battery — you lock and unlock by turning the key in the door barrel. If your remote “stopped working” and you own this version, there was never a battery to go flat: the doors were always meant to be locked by hand. Retrofitting genuine remote central locking to a take up! means adding hardware to the car, not just swapping the key, so it is a workshop job rather than a battery change.
Check It Worked
Step back a few metres and lock, then unlock, the up!. Full range should return instantly and the fob’s LED should flash crisply with each press. If the buttons work but only up close, the cell is either the wrong way round, not seated firmly under its clip, or a weak no-name battery — open the fob and check all three.
If a Fresh Cell Doesn’t Fix It
- Re-check the orientation and seating. A coin cell fitted upside down, or one not pressed fully under its retaining clip, is the single most common reason a “new” battery changes nothing.
- Clean the contacts. Wipe the metal terminals inside the fob with a dry cloth; a film of grease or light corrosion is enough to cause dropouts.
- Try the buttons right next to the car. If they now work at point-blank range only, the transmitter is weak — usually still the cell, occasionally the fob itself.
- Rule out the car’s own battery. A tired 12 V battery can make the up! slow to respond to the remote. If the car is also cranking lazily, sort the main battery first.
New Key or Spare — Why It’s a Dealer Job
Changing the coin cell leaves the fob’s existing coding untouched, so the remote keeps working with no programming needed. A brand-new key is a different matter: the blade has to be cut to your up!’s lock, and the transponder in the key must be matched to the car’s immobiliser with diagnostic equipment before it will start the engine. Blank keys are ordered against the vehicle’s VIN, which is why cutting and coding a replacement or a spare is a job for a VW dealer or an auto-locksmith. Keep the battery in your second key fresh too, and you’ll never be caught out with a single working remote.
Frequently Asked Questions
What battery does a VW up! key fob take?
The folding remote uses one CR2032 3-volt lithium coin cell. The button-less “take up!” key has no buttons and no battery at all.
Which way round does the coin cell go?
Match the way the old cell sat — note the printed “+” face before you lift it out and fit the new one the same way. Advice online disagrees on up-versus-down for VW keys, so copying the original is the reliable approach. Fitted the wrong way, the fob simply won’t transmit.
Do I have to reprogram the key after changing the battery?
No. A battery swap doesn’t affect the coding, so the remote works the moment you close the case. Only a completely new key needs programming to the immobiliser.
How do I open the up! flip key without breaking it?
Fold the metal blade closed, find the seam around the edge of the case, and gently twist a tape-wrapped flat screwdriver in it to part the two halves. Work around the joint rather than levering hard on one point.
My remote still won’t work with a new battery — what now?
Re-check the cell’s orientation and that it’s seated firmly, then clean the contacts. If the LED still won’t light with a known-good branded cell, the fob’s transmitter may have failed — but that’s far rarer than a flat or upside-down battery.
Can I still get into and drive the up! if the fob is dead?
Yes. The metal blade unlocks the driver’s door and starts the car as normal — the remote buttons only handle central locking, so a flat coin cell won’t strand you.
If your up!’s remote died suddenly right after the car battery was disconnected or went flat — rather than fading over weeks — the cause is more likely a pairing or electrical glitch than the coin cell, and the car may have logged a fault in the process. You can look up what any stored code means on autodtcs.com.
Independent guide — not affiliated with Volkswagen. Always follow your official service manual and safety precautions. Read our full disclaimer.