Diagnostic Aids

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

If oscilloscope is available, switching rate of heated oxygen sensor (bank No. 2, sensor No. 2) may compared to that of the A/F sensor (bank No. 2, sensor No. 1) by reading the waveform pattern to determine if malfunction exists. To check heated oxygen sensor waveform pattern, the A/F sensor (bank No. 2, sensor No. 1) must first be checked.

Connect oscilloscope between terminals No. 13 (White wire) and No. 17 (Brown wire) at ECM electrical connector E5. This is the AF2A+ terminal at ECM for A/F sensor (bank No. 2, sensor No. 1) and E1 terminal on ECM. ECM is located behind passenger's side kick panel, just below instrument panel. See Figure. For ECM electrical connector terminal identification, see Figure.

Start engine and warm engine to normal operating temperature. Ensure all accessories are off. Increase engine speed to 2500-3000 RPM for 3 minutes. Confirm that waveform pattern for A/F sensor (bank No. 2, sensor No. 1) oscillates at about .5 volt during feedback to ECM. See Figure. Disconnect oscilloscope and reconnect between terminals No. 15 (White wire) and No. 17 (Brown wire) at ECM electrical connector E5. This is the OX2B terminal for heated oxygen sensor (bank No. 2, sensor No. 2) and E1 terminal on ECM. Read heated oxygen sensor (bank No. 2, sensor No. 2) waveform pattern. If malfunction exists, the heated oxygen sensor waveform pattern will be almost the same as that for the A/F sensor. See Figure.