Cause of error code E59

Supply water temperature sensor is shorted. '0' Ohm

Solution for error code E59

1. Disconnect wire harness from high temperature supply switch. Measure resistance across terminals 2 and 4. Does temperature faal within ranges? 
Yes: Replace high temperature supply switch.
No: -> 2

2. Disconnect J5 from control module. Continuity between J5-11 and switch 2? Continuity between J5-3 and switch 4? 
Yes: Replace control module
No: Replace wires.