These instructions apply to the BMW 2 Series Mk2 (G42) 2021-present.
For other models, please choose your vehicle here.
Your BMW 2 Series (G42, 2021–present) switches the engine off at a standstill to save fuel and trim emissions in stop-go driving. When you’d rather keep it running — crawling traffic, a hot day, or before any under-bonnet work — you can switch Auto Start/Stop off. This is a comfort preference, not a fault: the system is working exactly as designed, and there is nothing wrong with the car if you decide you don’t want the engine cutting out at every red light.
How Auto Start/Stop Works on This Model
On the G42 the system constantly watches a set of conditions before it will cut the engine. It looks at the 12 V battery’s state of charge, the engine and coolant temperature, the interior climate demand, whether you’re on a slope, and whether the brake pedal is held firmly. Only when everything is comfortable does it shut the engine down, then restart it the instant you lift off the brake. Because the restart draws heavily on the battery, a healthy 12 V unit is central to the feature behaving smoothly — which is why it sometimes simply won’t stop the engine at all.
First, a Few Checks
- Have the engine running and the car fully at a standstill — you set the preference during a normal drive, not with the ignition off.
- Decide whether you want the physical button or the iDrive menu route; both do the same job.
- If you’re disabling it for under-bonnet work, switch off completely and remove the key so the engine can’t auto-restart.
- Expect to repeat this each time you drive — the setting does not stick between trips.
Turning It Off
- Look for the A inside a circular arrow button (often near the gear selector or by the iDrive controls) and press it once; the engine then stays running at stops.
- If your car has no physical button, open iDrive → Settings / Vehicle settings and switch Auto Start/Stop off there.
Why It Returns Each Drive
The G42 re-enables Auto Start/Stop every time you start the car. There’s no permanent factory off — switch it off again at the start of each drive if you prefer it disabled.
If the Engine Won’t Stop at Idle
If the system is on but the engine keeps running, it is almost always an inhibit condition rather than a fault. Common reasons on the G42:
- The 12 V battery charge is low — a tired or ageing battery is the single most common cause.
- The cabin still needs heating or cooling, so the engine stays on to drive the climate system.
- The engine or coolant hasn’t reached normal temperature yet on a cold morning.
- You’re stopped on a gradient, or the brake pedal isn’t pressed firmly enough.
- The bonnet is open, or the outside temperature is very high or very low.
- Steering is turned hard, or the car judges the stop will be too brief to bother.
Once It’s Done
Once you press the button, the indicator confirms the system is off and the engine stays running at every stop for the rest of the trip. Nothing else changes — fuel use rises marginally in heavy traffic, which is the trade-off. Next time you start the car it will be armed again, so repeat the button press if you want it off.
Frequently Asked Questions
How do I turn off auto stop/start on a BMW 2 Series?
Press the ‘A’ circled-arrow button, usually near the gear selector, or switch Auto Start/Stop off in iDrive vehicle settings. Either method disables it for the current drive and the indicator confirms the change. The engine will then keep running at every stop until you switch the car off.
Can I disable it permanently?
No — the G42 re-arms Auto Start/Stop at every engine start, so there is no factory permanent-off setting. You need to switch it off at the beginning of each drive. Some owners fit third-party memory modules for this, but that’s outside a standard owner procedure and can affect your warranty.
Why didn’t the engine stop today?
Low 12 V battery charge, ongoing climate demand, a cold or hot cabin, a gradient, or a brake pedal that isn’t held firmly will all keep the engine running. This is by design — the system only cuts the engine when every condition is comfortable, so intermittent behaviour is normal rather than a fault.
Does leaving it on harm the car?
No — the engine, starter and battery are all specified for the constant stop-start cycling, so leaving it enabled is fine. That said, a weak or ageing 12 V battery can make the system behave oddly, and repeated restarts put more demand on it than on a car without the feature.
Is it worse for the starter motor?
Cars with Auto Start/Stop use a heavy-duty starter (or belt-driven starter-generator) and a battery rated for the extra cycles, so normal use isn’t a problem. Wear only tends to show up if the battery is neglected, since a struggling battery makes each restart harder work for the system.
Should I switch it off before working under the bonnet?
Yes — if you’ll have hands near belts or the engine, switch the ignition fully off and remove the key so the engine cannot auto-restart. Simply pressing the A button disables stops during driving but the engine is still live, so it isn’t a substitute for shutting the car down.
If a start/stop fault shows, it usually points to the 12 V battery — see our 2 Series battery guide, or look the code up on autodtcs.com.
Independent guide — not affiliated with BMW. Always follow your official service manual and safety precautions. Read our full disclaimer.