DTC P0171: System Too Lean (Bank 1) (TO 12/2010); DTC P0172: System Too Rich (Bank 1) (TO 12/2010); DTC P0174: System Too Lean (Bank 2) (TO 12/2010); DTC P0175: System Too Rich (Bank 2) (TO 12/2010): Wiring Diagram
WARNING: This page is about a different car, the 2011 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
Air fuel ratio sensor (sensor 1) circuit: Refer to DTC P2195. Refer to WIRING DIAGRAM .
Mass air flow meter circuit: Refer to DTC P0102. Refer to WIRING DIAGRAM