ISG

📖 YOUCANIC Automotive Glossary

ISG (Idle Stop-Go), commonly called start-stop or auto start-stop, automatically shuts off the engine when the vehicle comes to a complete stop (foot on brake, in drive) and restarts it instantly when the brake is released or the accelerator is pressed. ISG reduces fuel consumption by 3-8% in city driving by eliminating idle fuel waste. The system monitors battery SOC, cabin temperature, engine temperature, and electrical load to determine when conditions are suitable for engine shutdown — if the battery is low, the cabin needs heating/cooling, or electrical demand is high, ISG keeps the engine running.

ISG requires an AGM (Absorbent Glass Mat) or EFB (Enhanced Flooded Battery) battery designed for frequent cycling — replacing with a standard flooded battery causes premature failure and ISG deactivation. Battery Registration (BRT) through the YOUCANIC UCAN-II is often required after battery replacement to re-enable ISG. Common complaints include ISG not activating (low battery SOC, extreme temperatures, specific conditions not met), rough restart feel, and the system being unwanted by the driver (most vehicles have a disable button, though it resets each drive cycle).