Front Heated Oxygen Sensor (HO2S)
FRONT HEATED OXYGEN SENSOR (HO2S) INSPECTION [L3]Front HO2S Current 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)
- Front HO2S current (PID: 02S11)
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 front HO2S current (PID: 02S11) is 0.25 mA or more while decelerating as shown in the figure.
- If not within the specification, inspect the HO2S for an open or short circuit. (See Front HO2S circuit open/short inspection (sensor).) Then if there is no malfunction in the wiring harness, replace the front HO2S.
Front HO2S circuit open/short inspection (sensor)
1. Disconnect the PCM connector.
2. Disconnect the front 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.
- Front HO2S terminal B and PCM terminal 2AD
- Front HO2S terminal D and PCM terminal 2AC
- Front HO2S terminal F and PCM terminal 2Z
Short circuit
- If there is continuity, there is a short circuit. Repair or replace the wiring harness.
- Front HO2S terminal B and body ground
- Front HO2S terminal B and power supply
- Front HO2S terminal D and power supply
- Front HO2S terminal D and body ground
- Front HO2S terminal F and power supply
- Front HO2S terminal F and body ground
Front HO2S heater resistance inspection
1. Disconnect the front HO2S connector.
2. Measure the resistance between front HO2S terminals A and E.
- If not within the specification, replace the front HO2S.
Front HO2S heater resistance
1-10 ohms
Front HO2S heater circuit open/short inspection (heater)
1. Disconnect the PCM connector.
2. Disconnect the front 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.
- Front HO2S terminal A and main relay terminal C
- Front HO2S terminal E and PCM terminal 2A
Short circuit
- If there is no continuity, there is a short circuit. Repair or replace the wiring harness.
- Front HO2S terminal A and body ground
- Front HO2S terminal E and power supply
- Front HO2S terminal E and body ground