Diagnosis & Repair

WARNING: This page is about a different car, the 2003 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

For diagnosis and repair procedure, see Fig 1-Fig 4 . When directed to perform confirmation driving pattern, see TEST DRIVE CONFIRMATION .

For HO2S circuit wiring diagram, see Figure. For ECM location, see Figure. For ECM connector terminal view, see Figure.

For vacuum or EVAP hose routing, see VACUUM DIAGRAMS article. For testing of systems or components, see BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article or SYSTEM & COMPONENT TESTING - 4-CYLINDER article. For removal and installation of components, see REMOVAL & INSTALLATION - 4-CYLINDER article.

Fig 1: DTCs P0171 & P0172 Diagnostic Procedure (Steps 1-3)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: DTCs P0171 & P0172 Diagnostic Procedure (Steps 4-7)

Fig 3: DTCs P0171 & P0172 Diagnostic Procedure (Steps 8-9)

Fig 4: DTCs P0171 & P0172 Diagnostic Procedure (Steps 10-12)