Why doesn't the start-stop function work after replacing the Cruze battery?

[McGarrett]

For the auto start-stop function to work, many conditions must be met, such as interior temperature, coolant temperature, voltage, whether the air conditioning is on, etc., all controlled by the onboard computer. Below is an introduction to Mazda's auto start-stop system: 1. Limitations: The auto start-stop function has usage restrictions. If the car battery doesn't have sufficient charge, the battery temperature is too high or too low, or the seatbelt isn't fastened while driving, the auto start-stop function won't work properly. 2. Principle: By installing an enhanced motor with idle start-stop capability in a traditional engine, the engine completely shuts off when idle stop conditions are met. When moving forward again is required, the idle start-stop motor quickly responds to the driver's start command, rapidly restarting the engine to reduce fuel consumption and exhaust emissions.

[McLillian]

I've encountered a similar situation where the start-stop system didn't work after replacing the battery, which could be due to several reasons. If the new battery isn't properly registered, the ECU won't detect its update and will disable the function as a protective measure. The start-stop system requires an AGM battery—never replace it with a regular one; otherwise, it will be automatically deactivated, a design feature strictly implemented in the Cruze. From my experience, it's best to drive about 10-15 kilometers after replacing the battery to allow the ECU to relearn driving patterns—activating the start-stop function a few times usually restores it. Another possibility is that the battery monitoring sensor isn't calibrated; try disconnecting the negative terminal for a few minutes before reconnecting. For safety, I recommend first verifying the battery model and registering it; if that doesn't work, visit a professional shop for OBD diagnostics rather than tampering yourself to avoid causing other electrical issues. Regular maintenance tip: periodically check your battery's health to prevent problems before they arise.