B737-700
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Last 90 Days 65; Flight Crew Type 65
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Overcame Equipment Problem; General Maintenance Action; General Flight Cancelled / Delayed
Aircraft
The Captain was flying and after takeoff the white FMC message dealing with the autothrottle appeared and the Pilot Flying noticed an amber EGT exceedance.  The autothrottles and VNAV were inoperative at that point after takeoff.  The TAT probe was indicating a higher than normal temperature which we determined to be the root cause of all the problems.  We consulted with the QRH and Dispatch and all agreed to air return to ZZZ without any further issues.
Just after takeoff the aircraft experienced a loss of data from the TAT probe (repeat gripe).  This initially manifested itself as an autothrottle limit error and a rapid increase in #1 EGT (yellow backfill on gage but no other indications) and loss of VNAV and related FMC functions.  We continued to climb to 16;000 feet MSL and informed ATC that we may need to return to ZZZ.  I passed aircraft control to the FO and initiated radio contact with Dispatch.  After initial contact; radio communications with Dispatch were lost; but Dispatch replied via ACARS that they agreed a return to ZZZ was prudent.  Release was amended.  ATC; cabin crew and passengers were informed; no emergency was declared.  The aircraft returned to ZZZ without incident.TAT failure is a high workload event similar to unreliable airspeed.  The number of items that rely on the TAT is huge; and once the event occurs there is (a) no real clue as to what the causal factor is; (b) no QRH guidance for the NN; and (c) a plethora of conflicting data and flight deck indications.  Thought should be given to educating our Pilot group to the risks and indications associated with TAT failure.
Flight Crew reported an air turn back after the TAT probe failed; causing the auto throttle to malfunction.