Cause of error code E65

Flue temperature sensor is shorted. '0' Ohm

Solution for error code E65

1. Disconnect wire harness from Vent Temperature Sensor. Measure Sensor resistance. Does resistance match estimated flue temperature?
Yes: -> 2
No: Replace Vent Temperature Sensor 

2. Disconnect harness from Control Module J5. Continuity in blue wires?
Yes: Replace Control Module 
No: Replace wires