How to run diagnostics on a Samsung front load washer?

How to run diagnostics on a Samsung front load washer involves entering diagnostic mode to check error codes and run test cycles. First method is to run calibration mode, with empty drum, press Power, then press and hold Temp and Delay End simultaneously for 3 seconds until CB appears, then press Start Pause to run calibration which checks drum rotation, water fill, and drain, takes about 3 minutes. Second method is diagnostic test mode for newer models, power off, press and hold Spin and Soil Level for 3 seconds, then press Power while holding, display shows t1, then press Start to cycle through tests t1 to tSt for water valves, drain pump, and spin. Third method is to check error codes in SmartThings app, connect washer to app and run self diagnostic. You can also run quick test, select any cycle, press and hold Smart Control for 3 seconds to see stored error codes. For manual diagnostics, check drain filter, check water inlet screens, and listen for unusual noises. If you get codes like 4C water supply, 5C drain, DC door lock, note code. Samsung service manual lists diagnostic codes. Always unplug for safety before inspecting.