These instructions apply to the Ford Mondeo Mk5 (CD391) 2014-2022.
For other models, please choose your vehicle here.
Your Ford Mondeo (Mk V, CD391, 2014–2022) with Auto-Start-Stop cuts the engine at a standstill to save fuel and reduce emissions in town driving. When you’d rather keep it running — stop-go traffic, a hot day, or before any under-bonnet work — one button turns it off. It’s a comfort choice rather than a repair: the system is doing its job when it shuts the engine off, and switching it off does no harm to the car.
How Auto-Start-Stop Works on This Model
On the Mk V Mondeo the system continuously checks several conditions before it will cut the engine. It monitors the 12 V battery’s state of charge, the engine coolant temperature, cabin heating or cooling demand, whether you’re on an incline, and how firmly the brake is applied. Only when all of these are satisfied does it shut the engine down, restarting instantly as you release the brake. The restart leans heavily on the battery, so a healthy 12 V unit is the single biggest factor in the feature working smoothly.
Getting Ready
- Have the engine running and the car at a complete standstill — you set this during a normal drive, not with the ignition off.
- Locate the A-in-arrow button before you set off so you’re not hunting for it in traffic.
- If you’re disabling it for engine-bay work, switch the ignition fully off so the engine can’t auto-restart.
- Expect to repeat the press each drive — the setting doesn’t carry over between trips.
Switching It Off
- Find the Auto-Start-Stop button — an A inside a circular arrow — on the dash or centre console.
- Press it once; the indicator confirms it’s off and the engine stays running at stops.
Why It Comes Back On
The Mondeo re-enables Auto-Start-Stop every time you start the car — 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 at Idle
If the system is on but the engine keeps running, it’s almost always an inhibit condition, not a fault. Common reasons on the Mk V Mondeo:
- The 12 V battery charge is low — an ageing or under-charged battery is the usual culprit.
- The cabin still needs heating or cooling, so the engine keeps the climate system fed.
- The engine hasn’t warmed to normal temperature yet, common on short or cold-morning trips.
- You’re stopped on a slope, or the brake isn’t held firmly enough.
- The bonnet is open, or outside temperatures are extreme.
- On the Hybrid, the engine is managed differently and won’t behave like the petrol or diesel.
What Happens Next
After pressing the button, the indicator confirms the system is off and the engine keeps running at every stop for the rest of the drive. Fuel use rises slightly in heavy traffic — that’s the trade-off. Because the setting resets, the car will be armed again next time you start it, so press the button again if you want it off.
Frequently Asked Questions
How do I turn off auto stop/start on a Ford Mondeo?
Press the ‘A’ circled-arrow button on the dash or console; the indicator shows it’s disabled for this drive. The engine will then keep running at every stop until you switch the car off. There’s no menu setting needed — the single button handles it on this model.
Can I disable it permanently?
No — the Mondeo re-arms Auto-Start-Stop each time you start the car, so it always defaults to on. You have to press the button per drive. Aftermarket memory modules exist that hold the setting, but that’s outside standard owner use and may affect warranty cover.
Why didn’t the engine stop today?
Low 12 V battery charge, ongoing climate demand, a cold engine, a gradient, or a brake pedal not held firmly will all keep the engine running. This is deliberate — the system only cuts the engine when conditions are comfortable, so days where it barely stops are normal rather than a fault.
Is it bad to leave it on?
No — the starter and battery are specified for the extra cycling, so leaving it enabled is fine for the car. The main caveat is the 12 V battery: as it ages the system can become erratic, stopping less often or not at all, which is a sign the battery needs checking rather than a fault in the feature.
Does it hurt fuel economy to switch it off?
Only marginally, and only in stop-go conditions where the engine would otherwise be idling. On a flowing run there’s virtually no difference because the system wouldn’t be cutting the engine anyway. Most owners who disable it do so for comfort in heavy traffic rather than to change consumption.
Should I turn it off before working under the bonnet?
Yes — if you’ll be near belts or moving parts, switch the ignition fully off rather than just pressing the A button. Disabling stops still leaves the engine live and able to run, so shutting the car down completely is the safe approach for any engine-bay work.
If a start/stop fault shows, it usually points to the 12 V battery — see our Mondeo battery guide, or look the code up on autodtcs.com.
Independent guide — not affiliated with Ford. Always follow your official service manual and safety precautions. Read our full disclaimer.