These instructions apply to the Peugeot 208 Mk2 (P21) 2019-Present.
For other models, please choose your vehicle here.
The second-generation Peugeot 208 (P21, 2019–present) shipped with a modern PSA-family remote, and depending on trim you have one of two keys: a folding “flip” remote on Active-grade cars, or the keyless hands-free smart fob that comes with Allure and GT. Both run on the same coin cell, but they open in different ways and the emergency blade is handled differently on each. If your 208 has started ignoring you from more than an arm’s length away, here is the exact cell it needs, how to open whichever key you own, and why a lost key ends at the dealer.
How to Tell the Fob Battery Is Dying
- You have to be almost touching the car. Range collapsing to a metre or less — or needing to hold the fob against the door handle — is the first and clearest warning.
- “Key not detected” on the i-Cockpit display. On keyless 208s a weak smart fob throws an on-dash message and the hands-free door handles stop responding; you can still start the car by holding the fob against the marked spot on the steering column.
- The lock/unlock is hit-and-miss. Buttons that work on the third or fourth press, especially on a cold morning, point to a cell that can no longer deliver its brief transmit current.
- No confirmation flash. If the little LED by the buttons stops blinking when you press them, the cell is essentially flat.
A coin cell in a 208 fob usually gives two to four years of service. A keyless fob left sitting by the front door, waking every time you pass it, tends to drain sooner than a plain remote that only transmits on a button press.
The Battery You Need
Both the folding remote and the keyless smart fob take a single CR2032 — a 3-volt lithium coin cell, 20 mm across, sold in every supermarket, phone shop and hardware store. Fit a fresh branded cell rather than a bargain multipack; thin or aged cells sag under load and can read as “short range” even straight out of the packet. Ignore any listing that suggests a CR1620 — that thinner cell belongs to older PSA flip keys, not the Mk2 208.
Method 1 — Folding “Flip” Remote
- Fold the metal blade closed so the body is easy to grip.
- Find the seam that runs around the edge of the fob. Slip a fingernail or a thin plastic tool (a guitar pick is ideal) into the gap and work your way round to unclip the two halves. Avoid a metal screwdriver where you can — it marks the plastic and can nick the board.
- Lift the old CR2032 out, noting which face pointed up before you disturb it.
- Drop the new cell in the same way round, press it home under its clip, then align the halves and squeeze until they click shut.
Method 2 — Keyless Hands-Free Smart Fob
- Release the emergency blade first: slide the catch on the base of the fob and draw the metal key straight out. The slot it leaves is your opening point.
- Insert a flat plastic tool into that slot (or the seam beside it) and gently twist to spring the case apart.
- Ease the flat CR2032 out from under its retaining tab, then fit the new one the same way round — the only rule that never fails is to match the cell you removed.
- Seat the fresh cell, clip the halves back together, and slide the emergency blade home until it latches.
⚠️ Get the orientation right. A coin cell forced in the wrong way round makes poor contact and can slowly discharge, leaving you with a key that seems dead again within days. Before you lift the old cell, take a quick phone photo of how it sits — then there is nothing to remember.
Did It Work?
Step back several metres and lock, then unlock, the car. Full range should return the instant the fresh cell is in. On a keyless 208 the “key not detected” message clears as soon as the car next reads a healthy fob — sometimes immediately, occasionally after you have started it once.
If a Fresh Cell Doesn’t Fix It
- Re-check the seating. The commonest cause of “the new battery didn’t work” is a cell fitted upside down or not fully under its clip. Pop it out and refit it against the orientation you noted.
- Clean the contacts. A film of finger grease or light corrosion on the terminals is enough to cause dropouts — wipe them with a dry cloth.
- Confirm the cell is genuinely fresh. A CR2032 that has sat in a drawer for a year can measure well under 3 volts. Try a second cell before assuming the fob has failed.
- Suspect the car, not the key? If the 208 is slow to wake and several electrical niggles arrived together, a tired 12 volt battery can mimic key faults.
New Key or Spare — Why It’s a Dealer Job
Changing the cell leaves the fob’s existing pairing untouched, so nothing needs reprogramming and the key works the moment it powers up. A replacement or additional key is a different story: Peugeot’s BSI immobiliser has to be accessed with the correct diagnostic equipment, and blank keys are supplied and coded against the car’s VIN. That puts a lost-key replacement firmly with a Peugeot dealer or an auto-locksmith — so keep the battery in your spare fresh too, and you are never one flat cell away from being stuck.
Frequently Asked Questions
What battery does a Peugeot 208 (2019 onward) key take?
A single CR2032 3-volt lithium coin cell, used by both the folding remote and the keyless hands-free fob. It is not the thinner CR1620 that older Peugeot flip keys use.
Which way round does the coin cell go?
Match the cell you removed. On the keyless smart fob the marked positive face generally sits downward; on the flip remote it tends to face up. Because trims vary, note the original orientation — or photograph it — before lifting the old cell out.
Do I have to reprogram the fob after a battery change?
No. The pairing lives in the fob’s memory and a battery swap does not disturb it, so the key works straight away. Only a brand-new key needs coding to the car.
How long should the battery last?
Typically two to four years. A keyless fob parked near the car, constantly waking to look for it, drains faster than a plain remote you only press when you need it.
My 208 key still won’t work with a new battery — what now?
Re-check the cell’s orientation and seating first, then clean the contacts and try a second known-good cell. If the LED still refuses to flash, the fob’s transmitter may have failed — uncommon next to a simple flat or upside-down cell, but it does happen.
Can I still drive if the fob is completely dead?
Yes. Use the emergency blade inside the fob to unlock the driver’s door, then hold the fob against the marked point on the steering column and press start — the keyless system is designed to read the fob at close range even with a flat cell, so a dead battery will not strand you.
If the remote quit abruptly right after the car battery was disconnected — rather than fading over weeks — the pairing, not the cell, is the more likely culprit, and any stored fault will point you there. You can look up what a logged code means on autodtcs.com.
Independent guide — not affiliated with Peugeot. Always follow your official service manual and safety precautions. Read our full disclaimer.