Why does the auto start-stop system still activate when the brake is pressed?
3 Answers
Start-stop systems operate based on the battery's charge level. If multiple electrical devices in the vehicle are turned on, the engine may start working after a few seconds. Here's an introduction to auto start-stop knowledge: 1. Limitations: The use of auto start-stop function is subject to certain conditions. It won't function properly if the car battery has insufficient charge, if the battery temperature is too high or too low, or if seat belts aren't fastened during driving. 2. Working Principle: By installing an enhanced motor with idle start-stop capability in traditional engines, the system completely shuts off the engine when idle stop conditions are met. When needing to move again, the idle start-stop motor quickly responds to the driver's command, rapidly restarting the engine to reduce fuel consumption and exhaust emissions.
I've encountered this issue with the auto start-stop system activating while braking. First, it's important to understand that the start-stop system has multiple activation conditions: the battery must have sufficient charge, and the coolant temperature needs to reach above 70°C. If you brake immediately after starting the car when the engine is still cold, the system won't shut off the engine. Also, check if you accidentally turned off the start-stop switch or activated the defroster function - these will force the system to keep running. I remember one winter when my start-stop kept failing, and it turned out to be low battery voltage; replacing the battery fixed it. My advice is to monitor when it activates, and if problems persist frequently, visit the dealership to read the vehicle's computer data stream.
There could be several reasons for this situation. Last year I studied the auto start-stop mechanism: the system continuously monitors parameters like steering wheel angle, seatbelt status, and air conditioning power. For example, when the AC is on with high cooling demand, the engine won't shut off when braking. Similarly, on steep slopes, it keeps running to prevent rolling back. Additionally, if the engine bay temperature sensor fails, the ECU assumes overheating and maintains operation for cooling. You could try operating on flat ground with AC off - if it still doesn't work, immediately check the sensor wiring.
