These instructions apply to the Vauxhall Astra Mk8 (L) 2022-Present.
For other models, please choose your vehicle here.
If the remote on your Vauxhall Astra (Mk8/L, 2022–Present) has stopped popping the locks and the dash shows “No key detected”, the coin cell inside the fob has almost certainly gone flat. You are not stranded. Every Astra L fob hides a metal emergency blade to get you in, and because this car shares its Stellantis platform with the latest Corsa and Peugeot 308, there is a short-range reader behind the START/STOP button so a keyless car still starts with a dead fob.
Most Astra L cars are keyless with a START/STOP button. Whichever trim you have, the backup method below gets you going. A “Key battery low” warning on the cluster is the car’s way of telling you to replace the cell soon.
Start a Keyless Astra L With a Dead Fob
On the Stellantis-platform Astra L the immobiliser can still read the fob at very close range. Do this:
- Get into the car first with the emergency blade (see the next section) — the door buttons will not respond on a flat fob.
- Sit in, press the brake pedal firmly and hold it down.
- Hold the flat face of the fob against the START/STOP button, or against the marked spot the handbook shows, so the chip sits right on the reader.
- With the fob still touching the button, press the button. The car powers the passive chip in the fob, recognises your key and releases the engine.
- The engine starts. If nothing happens first time, rotate the fob a few degrees and try again — the read zone is small.
Unlike the older GM Astra K, the Astra L does not use a cup-holder backup spot — holding the fob to the button is the method for this car. A “No key detected” message is your cue to use it.
Unlock the Astra L With the Emergency Key Blade
A metal blade folds into the fob for exactly this situation.
- Press the button on the corner of the fob to release the flip blade, or slide the back catch and pull the blade out.
- Go to the driver’s door. The lock barrel sits behind a small plastic cap on the door handle — slip the blade tip into the slot at the rear edge of the cap and prise the cover off.
- Insert the blade and turn it to unlock the driver’s door. The interior central-locking button frees the rest once you are inside.
Why a Flat Battery Does Not Strand You
The Astra L immobiliser never relied on the coin cell. Inside the fob is a passive transponder that draws its power from the car’s reader coil by induction, like a contactless bank card. The flat battery only kills the long-range radio that locks the doors from a distance. Hold the fob to the START/STOP button and the short-range coil powers the chip directly, so the car still knows it is your key.
Replace the Key Fob Battery
- Release and remove the emergency blade first — on the Astra L fob this helps the case split.
- Split the fob along its seam with a thin coin or plastic pry tool, working from the slot the blade left.
- Lift out the old cell. The Astra L fob uses a single CR2032 3V coin cell.
- Fit the new battery with the + side the same way up as the old one, handling it by the edges.
- Clip the case shut, push the blade back in and test the buttons. A fresh cell lasts roughly 2–3 years.
Frequently Asked Questions
Where do I hold the fob on a keyless Astra L? Against the START/STOP button, or the marked spot the handbook shows. That is where the backup reader sits on this Stellantis-platform car — not a cup holder.
Is the Astra L the same as the Astra K for this? No. The older GM Astra K uses a cup-holder backup spot; the newer Astra L reads the fob at the button. Use the method for your car’s generation.
Where is the hidden door lock on the Astra L? Behind a clip-off plastic cap on the driver’s door handle. Prise the cap from its rear edge to reveal the barrel.
Which battery does the Astra L fob take? A CR2032, sold in any supermarket or hardware shop.
It only started when I held the fob to the button — is something broken? That usually just means the fob battery is weak or flat. Fit a fresh CR2032; if it keeps happening with a new cell, the fob’s transmitter may be failing.
If a warning light stayed on after all this, you can look up what the code means on our sister site autodtcs.com.
Independent guide — not affiliated with Vauxhall. Always follow your official service manual and safety precautions. Read our full disclaimer.