These instructions apply to the Porsche 718 Boxster / Cayman 982 2016-Present.
For other models, please choose your vehicle here.
When the remote on a Porsche 718 (Type 982, 2016–present — Boxster and Cayman) starts working only from arm’s length, or the car greets you with a “Replace ignition key battery” message on the instrument display, the fix is nearly always the coin cell inside the key. The 718 ships with a single style of key — the familiar Porsche smart (keyless) fob shaped like the car’s own silhouette, with a hidden mechanical emergency blade — so there is only one procedure to learn. This guide covers the exact cell it takes, how to open the fob without marking that painted shell, and why a new key is the one job you can’t finish at home.
How to Tell the Fob Battery Is Dying
- Shrinking range. You find yourself standing right next to the door — or holding the fob against the handle — before it locks or unlocks. This is almost always the first sign.
- A dash message. The 718’s instrument cluster shows a “Replace ignition key battery” warning when it reads a weak fob. It typically appears as you get in and switch on, and it is the clearest confirmation that the cell — not the car — is the problem.
- Keyless entry gets fussy. If your car has Porsche Entry & Drive, the passive door-handle unlock and the dash push-button start become intermittent as the cell fades, even while the buttons still just about work up close.
- Cold-weather dropouts. A cell that is nearly flat sags further in the cold, so the fob may fail on a frosty morning and seem to recover once it warms up.
A CR2032 in a 718 key typically lasts two to four years. If yours is around that age and showing any of the above, fit a fresh cell before you start suspecting the receiver or the immobiliser.
The Battery You Need
The 718 smart key uses a single CR2032 — a 3-volt lithium coin cell, and the most common fob battery there is, sold in any supermarket, hardware shop or pharmacy. Buy a good-quality branded cell rather than the cheapest multipack: budget cells sag under the brief high current the transmitter draws and can give short range even when they read as “new”. Porsche fits the same CR2032 across its current range, so a spare from a household drawer is very likely the right size — but always confirm against the code printed on the cell you remove.
How to Replace the 718 Key Battery
- Release the emergency blade. Turn the fob over, press the small release catch on the side, and slide the mechanical key blade straight out. Set it aside — you’ll refit it last, and the recess it leaves is your way into the case.
- Open the back of the fob. With the blade removed, use a small flat-blade screwdriver in the recess (a plastic pry tool is kinder to the finish) and gently lever the cover off the back of the key. Work slowly around the seam — the clips are delicate and the shell is painted, so let the catches release rather than forcing them.
- Note the orientation, then lift out the old cell. Before you touch it, look at which face of the CR2032 is showing and how it sits under its retaining clip. Ease the spent cell out with a fingernail or the plastic tool.
- Fit the fresh CR2032 the same way round. Seat the new cell so its markings face exactly as the old one did — on the 718 the positive (+) face sits upward, toward the back cover you removed — and press it home under the clip. Handle it by the edges; finger grease on the flat faces can weaken the contact.
- Close it up and refit the blade. Press the back cover on until every clip clicks flush, then slide the emergency blade back in until it latches. Test all the buttons.
⚠️ Match the orientation exactly. A coin cell fitted upside down won’t power the fob and can slowly discharge against the contacts, so copy the way the old cell sat — the small ‘+’ and ‘−’ marks inside the holder confirm it if you’re unsure.
Did It Work?
Stand back a few metres and lock, then unlock, the car — full range should return at once. The “Replace ignition key battery” message clears the next time the 718 reads a healthy fob, which is usually immediately but occasionally takes one switch-on cycle. If you have Entry & Drive, confirm the door handles and the dash start button respond again without you touching a button.
If a Fresh Cell Doesn’t Fix It
- Re-check polarity and seating. A cell fitted the wrong way up, or one not fully under its clip, is by far the most common reason a “new” battery changes nothing. Reopen and confirm it matches the orientation you removed.
- Wipe the contacts. A smear of finger grease or a little corrosion on the terminals is enough to cause dropouts; clean them with a dry cloth and reseat the cell.
- Try the known-good spare. If your second 718 key works perfectly at range, the first fob’s transmitter may have failed — rare, but it happens.
- Rule out the car’s own battery. A weak 12 V battery can make a Porsche slow to wake and mimic key faults. If the whole car feels sluggish to respond, not just the key, that’s worth checking before you condemn the fob.
New Key or Spare — Why It’s a Dealer Job
Swapping the coin cell leaves the fob’s existing coding untouched, so nothing needs reprogramming and the key works the instant power returns. Cutting or coding a new key is a different matter: the 718’s immobiliser has to be accessed with Porsche diagnostic equipment, and blank fobs are ordered against the car’s VIN, often with proof of ownership. That makes adding a spare or replacing a lost key a job for a Porsche Centre or a specialist auto-locksmith — so keep the battery in your spare key fresh too, and you’re never down to a single working fob.
Frequently Asked Questions
What battery does a Porsche 718 key fob take?
A single CR2032 3-volt lithium coin cell — the same size Porsche uses across its current models, and available almost anywhere.
Which way up does the cell go in a 718 key?
The positive (+) face sits upward, toward the back cover. The surest guide is simply to match the orientation of the cell you removed; the ‘+’ and ‘−’ marks moulded inside the holder confirm it.
Do I need to reprogram the key after changing the battery?
No. A battery swap doesn’t affect the coding, so the fob works straight away. Only a brand-new key needs programming to the car.
How long should a 718 key battery last?
Typically two to four years. Leaving a keyless fob sitting close to the car so it wakes constantly, or heavy daily remote use, will shorten that.
The “Replace ignition key battery” message won’t clear — what now?
Recheck that the new cell is the right way up and fully seated, and clean the contacts. The warning usually clears the moment the car reads a good fob, but sometimes only after one switch-on cycle. If it persists with a known-good cell, the fob may need replacing.
Can I still drive the 718 if the fob is completely dead?
Yes. Use the emergency blade hidden in the fob to unlock the driver’s door, and hold the dead key against the marked spot on the steering column (or in the cup-holder area, per your car’s manual) so the car can read it, then start as normal. A flat cell won’t strand you.
If the remote died suddenly right after the car’s 12 V battery was disconnected — rather than fading over weeks — the cause is more likely a wider electrical or stored-fault issue than the coin cell. You can check what any logged code means on autodtcs.com.
Independent guide — not affiliated with Porsche. Always follow your official service manual and safety precautions. Read our full disclaimer.