We have 25 robots at our school, an increasing number of them are having trouble with sensor 2. In all tests sensor 1 behaves as expected, sensor 2 often doesn’t pick up the same white surface at all or it needs to be closer to the white surface to work properly. The dodgiest ones need a white surface to be ~3-5mm away to work.
What we have tested:
Different surfaces
Replacing batteries
With USB cable plugged in
Different ambient lighting
Upgrading firmware
Resetting Default Program
Cleaning the sensor (with air and cloth)
About 7 of them are having the same issue atm.