Arrived at a no heat call. Performed a full diagnostic check on a 2006 gas furnace. The system went through its sequence of operation and failed a the flame sensor. The system ran for about a minute but then cut off because the flame was not proven. We tested the flame sensor, it was faulty so we replaced it. We continue diagnosing the system and found a few additional concerns. We left the customer options for the other repairs. The system is currently working to the manufacturer’s specifications.