I’ve had a similar situation last year with a Bosch flow sensor I grabbed online. Took me a while to figure out the calibration, but what helped was slowly adjusting it while logging the data, instead of trying to rely on default settings. Also, I found some super useful tips on https://hydro-funk.com/equipment-catalog/elektronik/bosch for getting Bosch devices running smoothly. Once I tweaked it gradually, the readings became way more stable, and I was able to plug it straight into my Arduino without any glitches.