Diagnosis & Repair

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

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

NOTE: While performing this procedure, below are all related links to specifications and instructions.

For preliminary inspection with Toyota Hand-held tester or an Enhanced OBD II scan tool, see Figure. The preliminary inspection procedure of A/F CONTROL enables an output voltage check of A/F sensor and heated oxygen sensor. Use these HINTS during preliminary inspection:

A low A/F sensor voltage could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
A high A/F sensor voltage could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.

For diagnosis and repair procedure, see Fig 1-Fig 6 . When instructed to "Perform Confirmation Driving Pattern", go to TEST DRIVE CONFIRMATION .

For A/F sensor circuit wiring diagram, see Figure. When access to, or replacement of ECM is necessary, Engine Control Module (ECM) is located behind glove box. See Figure. For ECM connector terminal view, see Figure. 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, OVERHAUL & INSTALLATION - 4-CYLINDER article.

Fig 1: DTC P0134 Diagnostic Procedure (Steps 1-2)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: DTC P0134 Diagnostic Procedure (Step 2 Cont.)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 3: DTC P0134 Diagnostic Procedure (Steps 3-5)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 4: DTC P0134 Diagnostic Procedure (Steps 6-10)

Fig 5: DTC P0134 Diagnostic Procedure (Steps 11-15)

Fig 6: DTC P0134 Diagnostic Procedure (Steps 16-20)