These instructions apply to the Hyundai Tucson Mk4 (NX4) 2020-Present. For other models, please choose your vehicle here.
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Your Hyundai Tucson Mk4 (NX4, 2020–present) has an Idle Stop & Go (ISG) system that switches the engine off when you stop, to save fuel. If you’d rather keep it running in traffic, it’s one button to turn off. Here’s how, and why it sometimes won’t cut the engine. (On the full-hybrid Tucson the engine on/off is managed by the hybrid system instead.)
How ISG Works on the Tucson
Brake to a stop (automatic/DCT) or stop, select neutral and release the clutch (manual), and the engine shuts off. Lift the brake or dip the clutch and it restarts. It only operates once the engine is warm and the 12 V battery is healthy.
How to Switch It Off
- With the engine running, press the ISG / Auto Stop OFF button — an “A” inside a circular arrow, usually low on the dash or near the gear selector.
- A dash light confirms it’s off, and the engine idles normally at a stop.
How to Switch It Back On
Press the button again, or simply restart the car — ISG defaults back on every time you switch the ignition off and on. There’s no menu setting to make it permanently off.
Why It Sometimes Won’t Activate
- The engine isn’t up to temperature yet.
- The 12 V battery charge is low — common after a battery change or short trips; ISG is blocked to protect the battery.
- Cabin heating or demisting needs the engine running.
- The steering is turned, the car is on a slope, or you’re reversing.
If ISG stopped working after a battery change, let the battery fully charge — see our Tucson Mk4 battery guide.
Frequently Asked Questions
Does the Tucson remember my ISG setting?
No — it resets to on at every start. There’s no built-in option to keep it off.
Is it bad to keep using ISG?
No — the Tucson’s reinforced starter and battery are designed for frequent restarts, and it skips stops when the battery is low.
Why won’t the engine auto-stop?
Most often a cold engine, a low battery, or the climate system demanding the engine.
The ISG warning light is on — what now?
A lit ISG fault usually points to battery condition or a bonnet/seat-belt switch; have the code read if it persists.
If a warning light appeared alongside the fault, look up the code on autodtcs.com. To clear a service reminder, see our Tucson Mk4 service reset guide.
Disclaimer: The information on this page is provided for general guidance only. Always follow your official service manual and safety precautions when working on your vehicle. We are not responsible for errors, omissions, or any damage resulting from the use of this information.
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