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.
After confirming DTC P0125, use Toyota hand-held tester or scan tool to access CURRENT DATA to read heated oxygen sensor No. 1 output voltage. If output voltage is always less than .1 volt, heated oxygen sensor No. 1 circuit may be open or shorted. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.