Rear Heated Oxygen Sensor (HO2S) Inspection

REAR HEATED OXYGEN SENSOR (HO2S) INSPECTION

California Emission Regulation Applicable Model

NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.

Rear HO2S voltage inspection
1. Warm up the engine to normal operating temperature.
2. Using the WDS or equivalent, monitor the following:
- Vehicle speed (PID: VSS)
- Engine speed (PID: RPM)
- Rear HO2S voltage (PID: O2S13)

3. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 rpm or more.

4. Verify that the rear HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the rear HO2S voltage (PID: O2S13) is 0.3 V or less while decelerating as shown in the figure.
- If not within the specification, inspect the HO2S for an open or short circuit. (See Rear HO2S circuit open/short inspection (sensor).) Then if there is no malfunction in the wiring harness, replace the rear HO2S.

Rear HO2S circuit open/short inspection (sensor)

1. Disconnect the rear HO2S connector.
2. Measure the rear HO2S resistance between terminals C and D.
- If not within the specification, replace the rear HO2S.

Rear HO2S heater resistance
2 - 50 Ohms

Rear HO2S circuit open/short inspection (heater)

1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

Open circuit
- If there is no continuity, there is an open circuit. Repair or replace the wiring harness.
- HO2S terminal C and main relay terminal E
- HO2S terminal D and PCM terminal 2D

Short circuit
- If there is no continuity, there is a short circuit. Repair or replace the wiring harness.

Front and rear
- HO2S terminal C and body GND
- HO2S terminal D and power supply
- HO2S terminal D and body GND

Except for California Emission Regulation Applicable Model

NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.

Rear HO2S voltage inspection
1. Warm up the engine to normal operating temperature.
2. Using the WDS or equivalent, monitor the following:
- Vehicle speed (PID: VSS)
- Engine speed (PID: RPM)
- Rear HO2S voltage (PID: O2S12)

3. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 rpm or more.

4. Verify that the rear HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the rear HO2S voltage (PID: O2S12) is 0.3 V or less while decelerating as shown in the figure.
- If not within the specification, inspect the HO2S for an open or short circuit. (See Rear HO2S circuit open/short inspection (sensor).) Then if there is no malfunction in the wiring harness, replace the rear HO2S.

Rear HO2S circuit open/short inspection (sensor)

2. Measure the rear HO2S resistance between terminals C and D.
- If not within the specification, replace the rear HO2S.

Rear HO2S heater resistance
2 - 50 Ohms

Rear HO2S circuit open/short inspection (heater)