These instructions apply to the Vauxhall Mokka Mk2 (P2QO) 2020-Present.
For other models, please choose your vehicle here.
If the remote on your Vauxhall Mokka Mk2 (2020–present) — sold as the Opel Mokka B across the rest of Europe — only works from a step away, drops out in the cold, or has gone dead, the cause is almost always the coin cell inside it rather than the car. This second-generation Mokka rides on Stellantis’ CMP platform, sharing its one-piece smart-key case (with a hidden emergency blade) with the Corsa F and Peugeot 208. Depending on trim you have either a full keyless (proximity) fob that unlocks and starts the car in your pocket, or a remote-only button fob — but both take the same battery and open the same way. Here is how to spot a dying cell, the exact battery to buy, and the two-minute swap.
How to Tell the Fob Battery Is Dying
- Shrinking range. You have to be right next to the car, or almost touch the fob to the door handle, before it locks or unlocks. This is the classic first sign and it usually creeps up over a week or two.
- A dashboard warning. The Mokka’s driver information centre shows a low key-battery message (wording along the lines of “Key battery low” / “Remote control battery low”) when the smart fob’s cell is getting weak — a clear early warning to change it.
- Keyless entry stops waking the car. On proximity models you find yourself pressing the button instead of just pulling the handle, because the car can no longer “see” the fob as you approach.
- Cold-weather dropouts. A cell that is nearly flat sags further in the cold, so the fob may work fine in a warm house but fail on a frosty morning.
A coin cell in a Mokka fob typically lasts two to four years. A keyless fob tends to drain faster than a press-button remote because it is constantly listening for the car, so if yours is a proximity key and it is a couple of years old, a fresh cell is the first thing to try.
The Battery You Need
The Mokka Mk2 fob takes a single CR2032 — a 3-volt lithium coin cell, 20 mm across and 3.2 mm thick, the most common key-fob battery there is. You will find it in any supermarket, hardware shop or pound shop. Buy a good-quality branded cell: cheap no-name cells sag under the brief burst of current the transmitter draws and can give poor range even straight out of the packet. If you ever open the fob and find a slightly thinner CR2025 in there, a CR2032 is the correct like-for-like upgrade and will last a little longer — but check the number printed on the cell you remove before ordering, just to be certain.
How to Change the Battery
Both the keyless and the remote-only Mokka fobs are the same physical case, so this single procedure covers every trim. You only need the emergency blade itself or a small flat-blade screwdriver.
- Release the emergency key blade. Slide the small catch on the side or top of the fob and pull the metal mechanical key straight out. This is the same blade you would use to unlock the door if the battery were completely dead.
- Split the case at the seam. With the blade removed you expose a slot and a seam running around the edge of the fob. Insert the tip of the emergency blade (or a thin flat-blade screwdriver) into that slot and gently twist to pop the two halves of the case apart. It unclips — there is no screw to undo.
- Lift out the old cell. Note carefully which way up it sits before you remove it — take a quick photo on your phone if that helps. Ease it out from under its retaining clip.
- Fit the new CR2032 the same way round. Seat the fresh cell in exactly the orientation the old one came out, pressing it home under the clip so it sits flat against the contacts. Handle it by the edges; finger grease on the flat faces can hurt the connection.
- Clip the case back together until it snaps shut all the way round, then slide the emergency blade back in until it latches. Test every button.
⚠️ Match the orientation of the cell you removed. A coin cell fitted upside down will not power the fob and, left in, can slowly drain itself against the contacts. If you did not note which way it sat, the writing on the cell normally faces the side of the case you can see when it is open — but copying the old cell’s position is always the safe way to be sure.
Confirm It Worked
Stand a few metres from the car and lock, then unlock, it with the button. Full range should return straight away. On a keyless Mokka, walk up with the fob in your pocket and try the handle to confirm proximity entry is working again. Any low key-battery message in the driver information centre clears once the car reads a healthy fob — sometimes instantly, sometimes after one short drive.
If a Fresh Cell Doesn’t Fix It
- Re-check the orientation and seating. An upside-down or loosely seated cell is by far the most common reason a “new” battery still doesn’t work. Make sure it clicks firmly under its clip.
- Clean the contacts. Wipe the battery terminals and the cell’s faces with a dry cloth; a smear of grease or a little tarnish is enough to cause dropouts.
- Try the keyless back-up. If the car won’t recognise the fob at all, hold it against the marked spot (usually the start button or steering column) to start the engine via the back-up transponder — that confirms the key still talks to the car and points to a battery-contact issue rather than a dead fob.
- Suspect the car’s 12 V battery. A weak main battery can make the Mokka slow to wake and mimic key faults. If the whole car feels sluggish to respond, the 12 V battery is worth checking too.
New Key or Spare — Why It’s a Dealer Job
Changing the battery keeps the fob’s existing coding, so nothing needs reprogramming and the key works the moment you close the case. Adding a spare or replacing a lost key is a very different matter. The Mokka’s smart keys are the encrypted Stellantis type (a 433 MHz proximity fob with a coded transponder), and a blank has to be ordered against the car’s VIN and then paired to the immobiliser with dealer-level diagnostic equipment. That makes a new or additional key a job for a Vauxhall/Opel dealer or a properly equipped auto-locksmith — so it pays to keep the battery in your spare key fresh as well, and never let yourself get down to a single working fob.
Frequently Asked Questions
What battery does a Vauxhall Mokka Mk2 key fob take?
A single CR2032 3-volt lithium coin cell. The same cell fits both the keyless proximity fob and the press-button remote across every trim of the 2020-onward Mokka.
How do I open the Mokka key to change the battery?
Slide the catch and pull out the metal emergency blade, then push the blade tip or a small flat screwdriver into the slot it leaves and twist to unclip the two halves. There is no screw — the case simply snaps apart.
Do I need to reprogram the fob after fitting a new battery?
No. A battery change doesn’t affect the coding, so the fob and the keyless system carry on working immediately. Only a brand-new key needs programming.
How long should a Mokka key battery last?
Around two to four years. Keyless (proximity) fobs generally drain a little faster than press-button remotes because they are always listening for the car.
My key still won’t work after a new battery — what now?
First re-check that the cell is the right way up and seated firmly, then clean the contacts. If it still won’t respond, hold the fob against the start button to start the car on the back-up transponder; if that works, the problem is the battery contact, not the key itself.
Can I still drive the Mokka if the fob battery is completely dead?
Yes. Use the emergency blade to unlock the driver’s door, then hold the fob against the marked start-button spot; the car reads the key’s back-up transponder and starts normally, so a flat cell won’t leave you stranded.
If your Mokka’s remote died suddenly right after the 12 V battery was disconnected — rather than fading gradually — the fault is more likely a wake-up or pairing glitch than the coin cell, and it may have logged a fault code you can look up on autodtcs.com.
Independent guide — not affiliated with Vauxhall. Always follow your official service manual and safety precautions. Read our full disclaimer.