OBDII diagnostic code P2176 means the Powertrain Control Module (PCM) has detected that the Throttle Body Actuator (TAC) has not learned the correct position in which the throttle valve should be in the throttle body. Therefore, the TAC system is limited in its function because of this error.
When this happens, the fail-safe mode or limp mode is activated, preventing the engine from normal acceleration until the malfunction is corrected and the code is cleared. The P2176 code is stored when other codes that indicate troubles in the safety of the engine or powertrain components are present.
To begin a good diagnosis, it is advisable to first consult the Technical Service Bulletins (TSB). Also, note that the trouble code P2176 is informative, so you should perform a complete scan of the system and identify if other codes are set. Diagnose those codes first before proceeding with P2176.
Check all Accelerator Actuator Control (TAC) system cables and connectors for damage. Repair if necessary.
Check the throttle body to verify that it is not dirty. In case it has remains of elements that prevent its good operation, clean it.