Those system lean codes get triggered when the air fuel ratio becomes too lean. Which means the optimum air / fuel ratio has not met. Which can be due to a number of components. It could be for leak in the air intake, faulty fuel injector, exhaust leak, incorrect fuel pressure, bad mass air flow sensor etc.
I have attached the complete trouble shooting guide for the codes P0171 and P0174 below. Follow those steps as it can help you determine what the issue is.
Let me know of any questions.
Images (Click to enlarge)
Friday, July 29th, 2022 AT 4:00 PM