Rear Heated Oxygen Sensor (HO2S)
REAR HEATED OXYGEN SENSOR (HO2S) INSPECTION [L3]Rear HO2S voltage inspection
1. Warm up the engine to normal operating temperature.
2. Using the M-MDS, monitor the following:
- Vehicle speed (PID: VSS)
- Engine speed (PID: RPM)
- Rear HO2S voltage (PID: 02S12)
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: 02S12) 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 PCM connector.
2. Disconnect the rear HO2S connector.
3. 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.
- Rear HO2S terminal A and PCM terminal 2Q
- Rear HO2S terminal B and PCM terminal 2AV
Short circuit
- If there is continuity, there is a short circuit. Repair or replace the wiring harness.
- Rear HO2S terminal A and body ground
- Rear HO2S terminal A and power supply
- Rear HO2S terminal B and power supply
Rear HO2S heater resistance inspection
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 H025 circuit open/short inspection (heater)
1. Disconnect the PCM connector
2. Disconnect the rear H025 connector.
3. 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.
- Rear HO2S terminal C and ignition switch
- Rear HO2S terminal D and PCM terminal 2B
Short circuit
- If there is no continuity, there is a short circuit. Repair or replace the wiring harness.
- Rear H025 terminal C and body ground
- Rear HO2S terminal D and power supply
- Rear HO2S terminal D and body ground