Monitor Description
WARNING: This page is about a different car, the 2004 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.
The ECM monitors the rear heated oxygen sensor (HO2S) in the following 3 items:
- The HO2S voltage changes between Rich (more than 4.5 volts) and Lean (less than 4.5 volts) while the vehicle is running (repeating acceleration and deceleration) for 8 minutes. If not, the ECM interprets this as a malfunction, illuminates the MIL, and then sets DTC.
- The HO2S voltage does not remain at less than 0.05 volts for a long time while the vehicle is running (60% of the time in the 220 second-monitor, the sensor output is less than 0.05V). If it does, the ECM interprets this as a malfunction, illuminates the MIL, and then sets a DTC.
- The sensor's voltage drops to below 0.2 volts (extremely Lean status) immediately when the vehicle decelerates and the fuel cut is working for 7 seconds. if not, the ECM interprets this to mean the sensor's response feature has deteriorated, illuminates the MIL, and then sets DTC.