These instructions apply to the MG MG3 Mk1 (SZP1) 2011-2023. For other models, please choose your vehicle here.
Last updated:
When your MG3 (2011–2023) only locks from close range, the key battery is flat. It’s a quick swap with no reprogramming.
The Cell You Need
The MG3 remote takes a single CR2032 3 V coin cell. Buy one before you open the key.
Opening the Key
- Press the catch and pull out the mechanical key blade from the fob.
- Separate the case halves with a flat-bladed screwdriver in the slot.
- Remove the old CR2032 — note that it sits with the positive (+) side facing down.
- Fit the new cell the same way, clip the case together and refit the blade.
After the Swap
Lock and unlock once to confirm. A battery change keeps the existing pairing — no reprogramming needed.
Frequently Asked Questions
What battery does an MG3 key take?
A single CR2032 coin cell, fitted positive-side down.
Do I need to reprogram after changing it?
No — the key keeps its pairing through a battery change.
My key still won’t work — now what?
Use the blade in the driver’s door to unlock manually, then check the new cell is seated the right way up.
Which way up does the cell go?
Positive (+) facing down, as the original was fitted.
If the car won’t respond at all, the 12 V battery may be flat — see our MG3 battery guide. For a stored code, look it up on autodtcs.com.
Disclaimer: The information on this page is provided for general guidance only. Always follow your official service manual and safety precautions when working on your vehicle. We are not responsible for errors, omissions, or any damage resulting from the use of this information.
This website is an independent resource and is not affiliated with, endorsed by, or sponsored by MG. All trademarks and brand names belong to their respective owners.