Start the Car With a Dead Key Fob Battery

Last updated: June 11, 2026

Polestar 2 (2020–Present) shares Volvo’s SPA hardware, so it uses a twist START knob and a backup reader in the front cupholder. The car also offers a phone-as-key app and, from the 2024 model year, a key card — so a flat fob battery has several easy work-arounds and rarely leaves you stuck.

A “Key battery low” message normally appears on the centre display in the days before the cell fails. Take it as your prompt to deal with the battery early.

Starting the Polestar 2 with a dead key fob

1. Unlock and get into the car using the emergency key blade (see below), the key card, or the Polestar app.
2. Sit in the driver’s seat and press the brake pedal firmly.
3. Lift the rubber mat in the front cupholder of the tunnel console to expose the small key symbol at the bottom — the backup reader.
4. Lay the remote flat on that symbol so it sits over the reader coil.
5. With the brake still pressed, twist the START knob clockwise and release it. The car reads the key through the cupholder and powers up the drive system.
6. If you used the app or key card to get in, hold the brake and follow the on-screen prompt instead; the car keeps you authorised once it has recognised you.

Unlocking the door with the emergency key

1. Find the slide lever on the key-ring end of the fob and free the front cover, then pull out the metal emergency key blade.
2. Go to the driver’s door, where the keyhole hides behind a cover at the rear edge of the handle.
3. Insert the blade tip into the slot under the cover and lever the cover off to expose the lock barrel.
4. Turn the blade to unlock, then refit the handle cover.
5. The alarm may sound; it stops once the car recognises your key, card or phone inside.

Key card, phone key and backup reader

The Polestar 2 remote carries a battery-powered radio for the buttons plus a passive transponder for the immobiliser. The cupholder reader energises that transponder directly, so the car can confirm the security code with no usable fob battery. On top of that, the Polestar app turns a paired phone into a digital key over Bluetooth, and 2024-on cars add a credit-card-sized key card you tap on the same areas — either of these gets you in and started even if the fob is completely dead.

Replacing the key fob battery

The Polestar 2’s standard remote uses a CR2032 3V lithium coin cell; avoid rechargeables, whose lower 1.2V output upsets the fob. Note that the slim buttonless smart key supplied with some cars is sealed — its cell is not user-replaceable, so a flat one is a service-centre job; lean on the cupholder reader, key card or app in the meantime.

1. Pull out the emergency key blade to release the rear cover of the standard remote.
2. Slide the cover off and open the round battery cap with a coin.
3. Fit a fresh CR2032 positive (+) side up.
4. Refit the cap and cover and reinsert the blade.
5. Press a button by the car to confirm it responds; the warning clears at the next start.

Frequently Asked Questions

Where is the Polestar 2 backup reader? In the bottom of the front cupholder. Lift the rubber mat to find the key symbol and rest the remote on it, then twist the START knob with the brake pressed.

Can I start it with my phone if the fob is dead? Yes. A phone paired through the Polestar app works as a digital key over Bluetooth and lets you unlock and start the car without the fob.

What about the key card? Cars from the 2024 model year include a key card you can tap to unlock and start, which is independent of the fob battery.

Can I change the buttonless smart key’s battery? No. That slim key is sealed; a flat cell means a trip to a Polestar service centre. Use the cupholder reader, card or app until then.

What battery does the standard remote use? A CR2032 3V lithium coin cell.

If a warning light or stored fault code shows up after the fob goes flat, you can look it up on autodtcs.com.