Diagnosis & Repair

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

For wiring diagram, see Fig 1. For diagnosis and repair, see Fig 2-Fig 4 . For ECM location, see Figure. To check for intermittent problems, see INTERMITTENT PROBLEM CHECK under SELF-DIAGNOSTIC SYSTEM. To identify circuits referenced in testing, See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. For removal and installation of components, see REMOVAL & INSTALLATION - 4-CYLINDER article. To check ECM inputs and outputs, see PIN VOLTAGE CHARTS article.

Fig 1: DTC P0120 Wiring Diagram

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: DTC P0120 Diagnostic Procedure (Steps 1-3)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 3: DTC P0120 Diagnostic Procedure (Steps 4-5)

Fig 4: DTC P0120 Diagnostic Procedure (Steps 6-7)