2012 forester scanner code PO171

[retiredapache]

Had check engine light come on.Scanner gave codePO171.I replaced the MAS sensor, check engine light came back on within 2 mos. Scanner again gives same PO171 code. Found a loose hose clamp on intake, tightened it and cleared code by disconnecting battery. Drove about 100 miles and check engine light reappeared, again with codePO171, Any ideas as to where to look next?

 

[AZ-Subaru]

Google your subject and it will show O2 sensor for the exhaust in the results. Would do some reading though. Other things could cause that code.

 

[remy6908]

Injector(s) bad, fuel filter clogged, Fuel pressure regulator failed, pcv hoses leaking. Could be a number of things.
How many miles does the car have? If you found a vacuum line loose odds are there are others as well loose.