These instructions apply to the MG HS Mk2 2024-present.
For other models, please choose your vehicle here.
When the remote on your MG HS Mk2 (2024–present) starts working only up close — or the cluster shows “Remote Key Low Battery, Please Replace” — the coin cell inside the smart key needs renewing. The HS key takes a single CR2032 3 V lithium coin cell, and swapping it is a five-minute job that keeps the key paired to your car.
The Battery You Need
The MG HS Mk2 smart key uses a CR2032 3 V lithium coin cell — the most common fob battery there is. Buy a good-quality branded cell; budget multipack cells can sag under the transmitter’s current draw and give poor range even when new. Match the code on the cell you remove to be sure it reads CR2032.
How to Replace the MG HS Key Battery
- Release the emergency key. Press the button on the fob to eject the decorative trim, then slide out the backup mechanical key blade.
- Open the case. Insert a small flat-bladed tool into the seam on the side of the key and gently prise the cover off, separating the upper and lower halves.
- Note the orientation, then lift out the old CR2032 — see which way up it sits (the printed + face normally points up) before removing it.
- Fit the new CR2032 the same way up, handling it by the edges, and press it fully home under its clip so it makes firm contact.
- Reassemble. Clip the cover back on until the seam closes evenly, refit the mechanical key and the decorative trim, then test lock and unlock.
⚠️ Get the polarity right. A cell fitted upside down makes no contact and can slowly discharge against the terminals, leaving the key dead even with a “new” battery in it. Always match the way the old cell was sitting.
If a Fresh Cell Doesn’t Fix It
- Re-check the polarity and seating — positive face up, sitting flat under its clip against clean contacts.
- Wipe the contacts inside the fob with a dry cloth to clear any film or grease.
- Start the car once to let the key resynchronise; if range is still poor, the fob itself may be at fault.
- Stranded with a dead fob? You can still start the car — see our start the MG HS with a dead key fob guide.
New Key or Spare — Why It’s a Dealer Job
Changing the coin cell keeps the key’s coding, so it works the moment the case clicks shut. A brand-new or replacement smart key is different: it must be programmed to your HS by an MG Authorised Repairer, so adding a spare or replacing a lost key is a dealer job. Keep the battery in your spare key fresh too, so you are never down to one working key.
Frequently Asked Questions
What battery does the MG HS Mk2 key fob take?
A single CR2032 3 V lithium coin cell. MG recommends the CR2032 specifically; the code is printed on the cell you remove.
Do I need to reprogram the key after changing the battery?
No. A battery swap does not affect pairing, so the key works straight away. Programming is only needed for a brand-new or replacement key, which the dealer codes to the car.
Which way up does the cell go?
Match the orientation of the cell you removed — the printed + face normally sits upward. An upside-down cell makes no contact.
How long should the new battery last?
Typically two to three years on a smart key. Leaving the key close to the car so the keyless system keeps waking it shortens that.
Can I still drive if the fob battery is completely dead?
Yes. Use the mechanical blade to unlock, then hold the smart key in the standby-start position against the Start switch and press Start — see our dead key fob start guide.
Independent guide — not affiliated with MG. Always follow your official service manual and safety precautions. Read our full disclaimer.