Cause of error code E57

Flue temperature sensor is open. No continuity.

Solution for error code E57

1. Is harness plugged into vent temperature sensor? Is harness plugged into control module J5? 
Yes: -> 2
No: Insert harness

2. Disconnect harness from vent temperature sensor and control module J5. Continuity for each blue wire? 
Yes: -> 3
No: Replace wires 

3. Measure resistance across vent temperature sensor terminal. Does resiatance match estimated flue temperature? 
Yes: Replace control module.
No: Replace vent temperature sensor.