These instructions apply to the DS 4 Mk2 2021-Present.
For other models, please choose your vehicle here.
When the remote on a DS 4 (2021–present, Stellantis EMP2 platform) starts working only from arm’s length, ignores the first press, or stops locking the car altogether, the cause is almost always the coin cell inside the fob rather than anything wrong with the vehicle. DS sells this second-generation DS 4 as a keyless car, so the range gets a single hands-free smart key — a chunky proximity fob with a concealed mechanical blade — rather than the older Citroën-badged DS4’s folding flip key. That means one opening method to learn, one cell to buy, and a job you can finish on the driveway in a couple of minutes. Here is exactly how to do it, how to be sure the battery really is the problem, and why cutting a brand-new key is the one part you can’t do at home.
How to Tell the Fob Battery Is Dying
- Shrinking range. You have to stand right next to the DS 4 — or hold the fob against the door handle — before it responds. This gradual loss of range is the classic first sign of a tired cell.
- Keyless entry gets lazy. The hands-free door handles stop recognising the fob in your pocket, so you find yourself pressing the button manually to get in.
- A “key battery low” warning. The DS 4 shows a low-key-battery message in the driver’s display when the smart fob’s voltage drops; treat it as a prompt to change the cell soon, not an emergency.
- Cold-weather dropouts. A nearly flat cell sags further in the cold, so intermittent response on frosty mornings often means the battery is on its way out.
- You have to start it with the fob on the button. If the car only recognises the key when you hold it against the start button, the battery is almost certainly weak.
A coin cell in a DS 4 smart key typically lasts two to four years. Leaving the fob sitting close to the car — on a hall table by the driveway, for instance — keeps it “awake” and talking to the car, which shortens that life noticeably.
The Battery You Need
The DS 4 (2021–present) smart key takes a single CR2032 3-volt lithium coin cell — the same flat, roughly 20 mm cell used by most modern proximity fobs, and available in any supermarket, hardware shop or petrol station. Buy a fresh, good-quality branded cell rather than a bargain multipack: cheap cells sag under the brief burst of current the transmitter draws and can give short range even straight out of the packet. Note that this is the newer DS-badged DS 4; the earlier Citroën DS4 (2010–2018) used different keys, so ignore listings for that car when you buy.
How to Replace the DS 4 Smart-Key Battery
- Release the emergency blade first. Slide the small catch on the side of the fob and pull the concealed mechanical key blade straight out. That blade is what unlocks the door if the fob is completely dead, and removing it exposes the seam you need to open the case.
- Split the two halves. Insert a thin flat tool — a small plastic trim tool, a fingernail, or the emergency blade itself — into the seam the blade left behind and gently work it around to unclip the back cover. Take it slowly; the case is plastic and the clips are easy to snap if you force one corner.
- Note how the old cell sits, then lift it out. Before you touch it, look at which face of the coin cell is visible and which way up it lies under its retaining clip. Ease it out with a fingernail or the tip of the plastic tool — avoid a metal screwdriver against the terminals.
- Fit the new CR2032 the same way round. Handle the new cell by its edges only; skin oils on the flat faces can shorten its life. Seat it under the clip in exactly the orientation you removed the old one — on this fob the positive (+) face generally sits toward the back cover, but the golden rule is to copy what you took out.
- Close the case and refit the blade. Line up the two halves, make sure the buttons and circuit board are seated, and press the edges together until the clips snap home all the way round. Slide the mechanical blade back in until it latches, then test the fob.
⚠️ Match the polarity to the cell you removed. A coin cell fitted upside down won’t power the fob and can slowly discharge against the contacts. Because it’s easy to flip a CR2032 without noticing, always compare the new cell’s orientation against the old one before you close the case.
Did It Work?
Step back a few metres, lock the DS 4, then unlock it — full range should return immediately. Try the hands-free handles too: with a healthy cell the car should let you in without pressing anything. Any “key battery low” message clears once the car has read the fresh fob a time or two, so it may take a drive cycle rather than clearing the instant you shut the door.
If a Fresh Cell Doesn’t Fix It
- Re-check the polarity and seating. A cell that’s upside down, or not fully under its clip, is the single most common reason a “new” battery seems dead. Pop the case and look again.
- Clean the contacts and confirm the cell is fresh. A smear of finger grease or light corrosion on the terminals can cause dropouts; wipe them with a dry cloth. Coin cells can also sit flat on a shop shelf for years, so a healthy CR2032 should read close to 3 volts on a tester.
- Rule out the car’s own 12 V battery. If the DS 4 is generally slow to wake or several electrical niggles appear at once, a weak vehicle battery can mimic key faults — that’s a separate issue from the fob cell.
New Key or Spare — Why It’s a Dealer Job
Changing the coin cell keeps the fob’s existing pairing, so the car recognises it straight away with no reprogramming. A replacement or spare key is a different matter. The DS 4’s immobiliser is a secure Stellantis system: a blank fob has to be ordered against the car’s VIN, the mechanical blade cut to match, and the key coded to the immobiliser with dealer-level diagnostic equipment. That puts adding a spare or replacing a lost key firmly with a DS/Stellantis dealer or a specialist auto-locksmith. The practical takeaway is to keep the battery in your spare fresh as well, so you’re never relying on a single working key.
Frequently Asked Questions
What battery does a DS 4 (2021–present) key fob take?
A single CR2032 3-volt lithium coin cell. It’s the most common smart-key battery on the market, so any supermarket or hardware shop will stock it.
Which way round does the cell go?
Fit the new CR2032 the same way up as the one you removed — on this fob the positive (+) face generally sits toward the back cover. Copying the old cell’s orientation is the safest approach, because a cell fitted the wrong way won’t work and can drain against the contacts.
Do I need to reprogram the key after changing the battery?
No. A battery swap doesn’t touch the fob’s coding, so it works immediately. Only a brand-new key needs coding to the car’s immobiliser.
How long should a DS 4 key battery last?
Usually two to four years. Storing the fob right next to the car keeps it constantly awake and can shorten that, so keep spare keys away from where the DS 4 is parked.
My DS 4 key still won’t work after a new battery — what now?
Re-check the polarity and seating first, then wipe the contacts. If a known-good cell still doesn’t bring the fob back, the transmitter itself may have failed, which is rare and needs a replacement key coded by a dealer or locksmith.
Can I still get into and start the DS 4 if the fob is completely dead?
Yes. Pull the concealed mechanical blade from the fob to unlock the driver’s door, and the keyless system is designed to still start the car when you hold the dead fob against the start button or steering column — so a flat cell won’t strand you.
If your DS 4’s remote quit suddenly rather than fading — especially right after the 12 V battery was disconnected or went flat — the fault is more likely an electrical or pairing glitch than the coin cell, and the car may have logged a fault code you can look up on autodtcs.com.
Independent guide — not affiliated with DS. Always follow your official service manual and safety precautions. Read our full disclaimer.