Diagnostic Aids

WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

This DTC uses two-trip detection logic. 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 sensors may be checked by reading both heated oxygen sensor waveform patterns by connecting oscilloscope between terminals No. 17 (Brown wire) at ECM electrical connector E8 and No. 12 (White wire) for heated oxygen sensor No. 1, or No. 11 (Yellow wire) for heated oxygen sensor No. 2 at ECM electrical connector E10. This is the E1, OX1A and OX1B terminals on ECM. ECM is located behind the glove box. See Figure. For ECM electrical connector terminal identification, see Figure. Start engine and warm engine to normal operating temperature. Ensure all accessories are off. Drive vehicle at 55 MPH for at least 5 minutes. Read heated oxygen sensor No. 1 waveform pattern and ensure waveform pattern oscillates around .5 volt. See Figure. After reading heated oxygen sensor No. 1 waveform pattern, read heated oxygen sensor No. 2 waveform pattern. Heated oxygen sensor No. 2 waveform pattern should be a smooth line ranging from .6-.7 volt. If malfunction exists, the waveform pattern will be as displayed. See Figure.