These instructions apply to the MG ZS Mk1 (ZS11) 2017-2021.
For other models, please choose your vehicle here.
Your MG ZS (2017–2021) with stop/start shuts the engine off at a standstill to save fuel and cut emissions in traffic. When you’d rather keep it running — crawling traffic, a hot day, or before any under-bonnet work — one button switches it off. The circled-‘A’ symbol on the cluster only reports the system’s state; it’s a normal feature, not a warning, and watching it change through a journey is exactly how the ZS is meant to behave.
How Stop/Start Works on the ZS
Bring the ZS to rest with the clutch up in neutral, or on the brake in an automatic, and the engine cuts while the cabin, lights and audio stay alive on the 12 V battery. Dip the clutch or lift off the brake and it restarts almost instantly. The car only permits a stop when its inhibit conditions are satisfied: the battery must hold enough charge, the engine needs to be warm, and the cabin temperature has to be near the setting you’ve chosen. If any of those isn’t met, the engine simply keeps idling — nothing is wrong.
Getting Ready
- You only need the ignition on; no tools are required and the engine can be running or off.
- Decide whether you want it off for this trip only or every trip — the ZS has no permanent off, so you’ll repeat it.
- For under-bonnet work, switch stop/start off and the ignition fully off to rule out an auto-restart.
- Find the button before you set off so you’re not reaching for it in moving traffic.
Turning Stop/Start Off
- Locate the stop/start button — an A inside a circular arrow — on the dash or centre console.
- Press it once; the indicator confirms the system is off and the engine stays running at stops.
On ZS models that route it through the touchscreen, look under Vehicle / Settings for the stop-start (engine auto-stop) toggle.
Why It’s On Again Next Time
The ZS switches stop/start back on at every ignition cycle — there’s no permanent off. Press the button at the start of each drive if you don’t want it.
If the Engine Won’t Stop — or Won’t Stay Off
If a press seems to have no effect, or the engine keeps idling when you expect a stop, work through these first:
- Weak or cold 12 V battery. Easily the most common cause — the ZS holds the engine running to protect and charge a tired battery, particularly on short journeys and cold mornings.
- Cabin not yet at temperature. On a very hot or cold day the climate demand blocks stops until the interior settles.
- Cold engine. Straight after a cold start the engine stays running until it warms through.
- Clutch or brake input. In a manual the engine only stops in neutral with the clutch fully up; in an auto the brake must be held firmly and the car fully stopped.
- On a slope, the ZS may skip the stop for stability reasons.
- You’ve just switched it off — if the indicator shows off, that’s the system working, not a fault.
- If a warning symbol stays lit while the system is genuinely disabled, have the 12 V battery load-tested before looking further.
What Happens Next
Once switched off, the button’s indicator stays lit and the engine idles normally at every stop for the rest of the drive. When you next start the ZS the system re-arms itself and the light returns to its ready state — press again if you want it off. Nothing is saved between trips, and no warning should linger once the ignition is cycled.
Frequently Asked Questions
How do I turn off auto stop/start on an MG ZS?
Press the circled-‘A’ button on the dash or console once and the indicator confirms the engine will idle at stops rather than cutting out. On cars without the physical button, open the touchscreen Vehicle or Settings menu and switch the stop-start (engine auto-stop) toggle off. Either way the change only applies to the current drive.
Can I disable it permanently?
No — the ZS re-enables stop/start automatically each time you start the car, and there’s no factory option to keep it off for good. The practical approach is to press the button at the start of any journey where you don’t want the engine cutting out, such as heavy traffic or a hot day when you want uninterrupted climate output.
Why didn’t the engine stop today?
A stop only happens when the conditions line up: enough 12 V charge, a warm engine, and a cabin near your set temperature. Low charge, a cold engine, strong heating or cooling demand, or resting on a gradient will all keep the engine running by design. It’s normal protective behaviour rather than a malfunction.
Is it bad to leave it on?
No — the ZS is built for regular stop/start cycling, with a starter and battery suited to it. The usual reason it feels erratic is a tired 12 V battery, which cuts how often a stop is allowed. If the engine stops far less often than it once did, check the battery’s health before anything else.
Does stop/start wear out the starter or battery?
Not in normal use — the ZS uses uprated components designed for frequent cycling, and it won’t auto-stop when the battery can’t support a clean restart. As the battery ages, stops naturally become rarer. Fitting the correct replacement battery type when needed keeps the system behaving as intended.
Why does it work in summer but not on cold mornings?
Cold weather is harder on the 12 V battery and the engine takes longer to reach operating temperature, so the ZS holds off stops until both are ready. Strong cabin heating demand adds to that. As the drive continues and everything warms up, you should find the engine begins stopping normally again.
If a stop/start fault shows, it usually points to the 12 V battery — see our ZS battery guide, or look the code up on autodtcs.com.
Independent guide — not affiliated with MG. Always follow your official service manual and safety precautions. Read our full disclaimer.