This is annoying (suddenly unresponsive)

[Pete1w]

Returned to the car after a long 14 hour shift at work, pressed the button to unlock the car, it unlocked and lit up as standard. I got in the car and nothing, zilch, nada, dead as a dodo. Couldn't lock it so totally unresponsive. Called the AA and they gave me a time slot which I couldn't wait for so just left it at work. Returned today with the spare key and still nothing. Not great for a car we've only had for 2 months. I'm ringing the AA when I finish work so hopefully it's a quick fix but it doesn't fill me with confidence going forward. Anyone else had this issue

 

[ReintjeWA]

A few similar stories around here I think, might just be that your 12V battery is knackered. Any chance you can get a booster on it? A co-worker maybe?

Post in thread 'MG4 won't unlock or start 10 hours after last use'

Sep 11, 2025

Update: it was the 12v. It was completely dead. Had to have it replaced. Car is only 2 weeks old. Was annoying but I’m thankful I got the MG assist

Hi, it is a good idea to keep a booster pack in your car. It's got me out of trouble twice.

• Jomarkh

• 

 

[Everest]

Have you tried doing a "ctrl-alt-del"... AKA, removing -ve side of 12V battery with 10mm spanner - wait a bit, jump up and down 3 times, pat your head and then reconnect the battery to see if it springs into life?

 

[ReintjeWA]

Have you tried doing a "ctrl-alt-del"... AKA, removing -ve side of 12v battery with 10mm spanner - wait a bit, jump up and down 3 times, pat your head and then reconnect the battery to see if it springs into life?

MG should hand these out with every purchase haha

Gear Spanner Keyring 10mm

The 10mm Gear Spanner Key Ring is a compact, take-anywhere tool perfect for small applications. Featuring a 72-teeth single-way ratcheting mechanism, this handy key ring is crafted from durable Chrome Vanadium Steel (Cr-V). Whether for quick fixes or as a fun fidget tool, it's a great addition...

www.kincrome.com.au

 

[OriginalBigAl]

I have made up a long (6m) 2 core lead out of flexible 4mm² cable with 4 crocodile clips , one on each end of each conductor to act as a battery booster from a sympathetic fellow motorist, should the worst occur , as a substitute for a battery booster which could be left impotent unless tended to.
It will only need enough umph/ capacity to wake up the car so the HV battery can take over its normal charging duties.
The return of colder temperatures and cars now approaching 2/3/4 years old might make the content of the OPs post a more regular occurrence.

 

[Pete1w]

A few similar stories around here I think, might just be that your 12v battery is knackered. Any chance you can get a booster on it? A co-worker maybe?

Post in thread 'MG4 won't unlock or start 10 hours after last use'

Sep 11, 2025

Update: it was the 12v. It was completely dead. Had to have it replaced. Car is only 2 weeks old. Was annoying but I’m thankful I got the MG assist

Hi, it is a good idea to keep a booster pack in your car. It's got me out of trouble twice.

• Jomarkh

• 

I wouldn't even know where to find the 12V battery.

 

[Chrisdriving]

I wouldn't even know where to find the 12v battery.

Really!!!!!

 

[Pete1w]

Really!!!!!

Really....... Is it in the instruction manual? Why would I need to know this information?

 

[Jomarkh]

Returned to the car after a long 14 hour shift at work, pressed the button to unlock the car, it unlocked and lit up as standard. I got in the car and nothing, zilch, nada, dead as a dodo. Couldn't lock it so totally unresponsive. Called the AA and they gave me a time slot which I couldn't wait for so just left it at work. Returned today with the spare key and still nothing. Not great for a car we've only had for 2 months. I'm ringing the AA when I finish work so hopefully it's a quick fix but it doesn't fill me with confidence going forward. Anyone else had this issue

There a few threads on what to carry in your boot or frunk as a get out of jail card.
The booster pack is top of the list followed by a 10mm spanner.

 

[Pete1w]

There a few threads on what to carry in you boot or fruck as a get out of jail card.
The booster pack is top of the list followed by a 10mm spanner

It looks like I've got some investigating to do. I guess things like this aren't an issue until it actually happens to you..

 

[ReintjeWA]

I wouldn't even know where to find the 12v battery.

Pop the hood, should be at the right hand side, towards the back (or towards the windscreen so to speak).

If yours has an aftermarket frunk it might be hidden from view and harder to access. You should be fine with clipping something on the positive terminal, and using the chassis as earth, instead of trying to get a clip on the other side of the battery.

 

[Everest]

Why would I need to know this information?

I think you have a reason

 

[Tuareg]

Really....... Is it in the instruction manual? Why would I need to know this information?

It's under the front hood as in most cars. A few have them in the back like some BMWs. Takes a few seconds to go take a look. You'll need to know this information if you get a problem such as you have right now.

 

[Pete1w]

I think you have a reason

I clearly do now. If this is a known fault i need all the information.

 

[Bam Bam]

If this is a known fault i need all the information.

I'm not sure about 'known fault,' but it is certainly an issue for all cars since they had batteries (rather than crankshafts) that the battery can go flat or fail.

Our previous (petrol) car was a nightmare for batteries. We didn't use the car much and it had some kind of drain and so it chewed through them.

Had a 12V battery charger for that reason but in the end we got a remote kill switch so it could be disconnected when not in use.

 

[ReintjeWA]

You could look at the sticker underneath the parcel shelf to see what the build date is for the car, it may give an indication on how old the 12V battery is. Is the car new, or new to you?

Even if the car is new from the dealer, it may have been sat in a lot for ages, deteriorating the 12V battery.

Thread 'Build Date'

Nov 1, 2023

Is it easy to find?

• securespark
• build date electric vehicle forum mg4
• Replies: 44
• Forum: MG4 EV Forum

 

[Pete1w]

You could look at the sticker underneath the parcel shelf to see what the build date is for the car, it may give an indication on how old the 12V battery is. Is the car new, or new to you?

Even if the car is new from the dealer, it may have been sat in a lot for ages, deteriorating the 12V battery.

Thread 'Build Date'

Nov 1, 2023

Is it easy to find?

• securespark
• build date electric vehicle forum mg4
• Replies: 44
• Forum: MG4 EV Forum

I'm hoping that if it is the 12V battery and it is knackered, then it is fully covered under the warranty.

 

[ReintjeWA]

I'm hoping that if it is the 12v battery and it is knackered, then it is fully covered under the warranty.

The battery might be fine, it might be loose connections, also a very common fault with UK delivered cars I believe.

12V battery is only covered for 12 months, and "All 12V Battery claims are limited to a maximum £100.00 pay out."

https://www.mg.co.uk/sites/default/files/2021-10/MG_Online_Warranty_Statement_October_2021.pdf

Before it get's to that though, I wouldn't rely too much on the willingness of the UK dealership network to do any warranty work, judging on what's been reported on the forum.

Either way do keep us up to date, everyone's experiences help.

 

[Anon70]

"Why would I need to know this information?"

These days knowing how to check your battery is part of the driving test

Basics (skills 1 to 4) - Ready to Pass?

Basic skills you need to pass your driving test, including understanding legal rules, doing safety and cockpit checks and car security.

readytopass.campaign.gov.uk

 

[Pete1w]

"Why would I need to know this information?"

These days knowing how to check your battery is part of the driving test

Basics (skills 1 to 4) - Ready to Pass?

Basic skills you need to pass your driving test, including understanding legal rules, doing safety and cockpit checks and car security.

readytopass.campaign.gov.uk

Good job I took my test 30 years ago.