These instructions apply to the Hyundai i40 Mk1 (VF) 2011-2019.
For other models, please choose your vehicle here.
The Hyundai i40 (VF, 2011–2019) with Idle Stop & Go (ISG) shuts the engine off at a standstill to save fuel. If you would rather it stayed running — in traffic, when manoeuvring or towing — you can switch it off with one button.
How to Switch ISG Off (or Back On)
- With the engine running, find the ISG OFF button — an “A” inside a circular arrow, low on the dash by the light switches.
- Press it once. The ISG OFF indicator lights up to confirm auto stop is disabled, and the engine idles normally at a stop.
- To turn ISG back on, press the button again, or simply restart the car — ISG defaults to on every time you start the engine.
Why ISG May Not Stop the Engine
- The engine or cabin is still warming up, or it is very cold or hot outside.
- The 12 V battery charge is low — ISG needs a healthy battery to restart reliably.
- You are on a steep slope, or the climate system is working hard.
Frequently Asked Questions
Does ISG stay off after I switch it off?
No. The setting resets each time you start the car, so ISG is on by default at every start. Press the ISG OFF button again if you want it disabled for that drive.
Is it bad to turn ISG off?
No. The button is there for exactly that. You lose a little fuel economy in town, but the engine and starter are unaffected.
Why won’t my engine auto-stop even with ISG on?
The system only stops the engine when conditions are met — engine warm, battery healthy, not on a steep hill. A tired 12 V battery is the most common reason it stops working.
If a warning light stays on afterwards, look the code up on our sister site autodtcs.com to see what it means.
Independent guide — not affiliated with Hyundai. Always follow your official service manual and safety precautions. Read our full disclaimer.