What Causes the Engine Start-Stop Light to Illuminate?
2 Answers
The engine start-stop light illuminates due to: damage to the clutch switch or battery negative sensor. The engine start-stop technology automatically shuts off the engine when the vehicle comes to a temporary stop during driving and restarts the engine system when it's time to move forward again. Reasons for start-stop system malfunctions include: 1. Battery sensor failure; 2. Vacuum sensor failure; 3. Brake switch failure; 4. Electronic vacuum pump failure; 5. Issues with the start-stop system control circuit; 6. Start-stop switch failure. It's important to note that the automatic start-stop function should not be activated in waterlogged areas to prevent sudden stops that could allow water to enter the engine. Additionally, avoid using the start-stop system on slopes to prevent the vehicle from sliding.
Last month, the start-stop light in my car also came on, which scared me into checking the manual immediately. The main reason was insufficient battery voltage, as the start-stop function requires a stable 12.8V or higher to operate. Another reason could be the weather being too hot with the air conditioning turned up too high, causing the engine to prioritize maintaining cooling, at which point the system automatically suspends the start-stop function. Once, right after refueling at a gas station, the light came on because my seatbelt wasn't fastened properly. Additionally, not pressing the brake pedal firmly enough or abnormal engine temperature can also trigger the warning. If all these scenarios are ruled out, it's likely an issue with the wheel speed sensor or the ECU control unit. I recommend using an OBD scanner to read the fault codes first. That's how I found out last time that it was due to an aging battery, and replacing it solved the problem.
