The Sauer‑Danfoss MC300 AT300407 is a micro‑transmission controller designed for mobile off‑highway hydraulic and electro‑hydraulic systems, featuring multi‑loop control and CAN network capability. Common failure points in this class include power supply degradation (voltage spikes or brownouts), I/O module wear, firmware corruption, and PCB solder joint fatigue due to vibration. First‑check diagnostics: verify the 24 V/48 V input rail with a multimeter; inspect all connectors for corrosion or loose contacts; review any stored error codes via CAN interface or local diagnostic port; and visually examine the board for burnt components or cracked traces before proceeding with firmware reflash or component replacement.[oss-gpt-20b]