Replace the Key Fob Battery

Last updated: June 6, 2026

A weak key is the usual reason a Vauxhall Astra K (Mk7, 2015–2021) — Opel Astra — stops locking from a distance or asks you to hold the fob to the start button. The Astra K key takes a single CR2032 and the change takes a couple of minutes.

Battery You Need

A single CR2032 3 V coin cell — the standard Vauxhall/Opel key battery.

How to Replace the Key Battery

1. If your key has one, slide out the emergency blade using the release catch.
2. Use a small screwdriver to split the key cover and remove it.
3. Lift out the old CR2032, noting which way up it sits — don’t touch the terminals.
4. Fit the new cell the same way up, observing polarity.
5. Refit the cover and the blade.

Lock and unlock from a few metres to confirm.

If It Still Won’t Work

• Start the car anyway — on keyless cars, hold the fob against the start button as you press; the car reads the transponder directly.
• Lock manually with the emergency blade in the driver’s door.

Frequently Asked Questions

What battery does the Vauxhall Astra K key take?

A single CR2032 3 V coin cell.

Do I need to reprogram the key after changing the battery?

No — it pairs again as soon as power is restored.

How do I open the Astra K key?

Slide out the emergency blade, then split the cover with a small screwdriver.

My key still won’t start the car — what now?

Hold the fob against the start button as you press it.

For a no-start with a warning light, check the code on autodtcs.com. See also our Astra K battery guide if the car is dead.