What engine, year and mileage? What air filter are you using? Clean the MAF. What scanner is it? You might be able to download instructions or the manual.
Some reasons for P0172 from TSB.
P0172 - System Too Rich (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The code sets when the adaptive fuel tables reach a lean calibrated limit.
Fuel System:
�· Excessive fuel pressure
�· Leaking/contaminated fuel injectors
�· Vapor recovery system concern
Base Engine:
�· Oil overfill
�· Cam timing concern
�· Low cylinder compression
�· Excessive engine wear
Powertrain Control System:
�· PCM concern
Induction System:
�· MAF contamination
