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Oxygen Sensor: Testing and Inspection

HEATED OXYGEN SENSOR (HO2S) INSPECTION[L3 WITH TC]

NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart. (See HOW TO USE THIS MANUAL.)

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: O2S11)

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: O2S11) 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. (Seed Front HO2S Circuit Open/Short Inspection (Sensor).) Then if there is no malfunction in the wiring harness, replace the front HO2S.

Front HO2S Heater Resistance Inspection
1. Disconnect the front HO2S connector.




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

Front H02S heater resistance : 1 - 10 ohms

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 in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness.
- Front H02S terminal 1A and PCM terminal 2AD
- Front H02S terminal 18 and PCM terminal 2AC
- Front H02S terminal 1C and PCM terminal 2Z

Short circuit
- If there is continuity in the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
- Front HO2S terminal 1A and body ground
- Front HO2S terminal 1A and power supply
- Front HO2S terminal 1B and body ground
- Front HO2S terminal 1B and power supply
- Front HO2S terminal 1C and body ground
- Front HO2S terminal 1C and power supply

Rear H02S 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: 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. (SeeO1-4OB-42 Rear HO2S Circuit Open/Short Inspection.) Then if there is no malfunction in the wiring harness, replace the rear HO2S.







Rear H02S Circuit Open/Short Inspection
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 1BC

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 HO2S.

Rear HO2S heater resistance : 2 - 50 ohms







Rear H02S Heater Circuit Open/Short Inspection (Heater)
1. Disconnect the PCM connector.
2. Disconnect the rear HO2S connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity check)

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 2D Short circuit
- If there is no continuity, there is a

short circuit
- Repair or replace the wiring harness. Rear
- Rear HO2S terminal A and body ground
- Rear HO2S terminal B and power supply
- Rear HO2S terminal B and body ground
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