I took my car to Autozone & got the codes...PO171 - System too lean (bank 1), and PO174 - System too lean (bank2). At the bottom it says "No faults detected". Can someone please tell me what this means?
If DTC 171 is also set, this indicates that both banks of the engine are operating lean. Inspect any items that would cause both banks to operate lean.
Inspect all areas of the engine for a vacuum leak. Also, inspect the PCV system for any leaks. Make sure that the engine oil fill cap is in place and tight. Check that the engine oil dip stick is fully seated.
Fuel pressure: The system will be lean if the pressure is too low. It may be necessary to monitor the fuel pressure while driving the vehicle at various road speeds and/or loads in order to confirm.
Fuel contamination: Water, in even small amounts, near the in-tank fuel pump inlet, can be delivered to the injector. The water causes a lean exhaust and can set DTC P0174.
Hope this helps.
P.S. A subscription to alldata and a service manual is almost necessary to owning a cadillac catera infact they should come with them