These instructions apply to the MG HS Mk1 2019-present. For other models, please choose your vehicle here.
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Renewing a flat battery or disconnecting for other work on your MG HS (2019–present)? The 12 V battery is in the engine bay. Do it in the right order and the car relearns its settings cleanly.
Where the Battery Is
Open the bonnet — the 12 V battery sits in the engine compartment, usually under a plastic cover. On the petrol HS there is no high-voltage system; on the HS PHEV (e-HS / Plug-in) the 12 V battery is still the owner-serviceable one, but never touch the orange high-voltage cabling — that’s a workshop task.
Disconnecting
- Switch everything off, remove the key and wait a couple of minutes.
- Lift the cover and slacken the negative (−, black) terminal first; lift it clear.
- Release the positive (+, red) clamp only if you’re removing the battery.
Reconnecting
- Fit positive first, then negative, and tighten both firmly.
- Switch the ignition on, wait, then start.
Afterwards
Re-set the clock/radio and re-store your tyre pressures. Let the car sit a minute before driving so the systems re-initialise.
Frequently Asked Questions
Where is the battery on an MG HS?
In the engine bay under a plastic cover — a standard 12 V battery.
Which terminal comes off first?
Negative (−) off first; positive (+) on first when reconnecting.
Is the PHEV safe to work on?
The 12 V battery is fine; never touch the orange high-voltage cables — leave those to a workshop.
Do I need to code a new battery?
For a like-for-like replacement, no coding is needed for normal running.
This is a common job. If a warning light stays on afterwards, check the code 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.
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