TYM Tractor Breakdown! What Happened? What's "LIMP MODE"?

What happens here

This project details the troubleshooting process for a TYM T1104 tractor experiencing 'limp mode' due to issues with its Diesel Exhaust Fluid (DEF) emissions system. The owner attempts several common DIY fixes, including battery resets, forced regeneration cycles, and replacing the DEF fluid, to resolve persistent warning lights and a lack of throttle response, ultimately concluding that professional service is required.