AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) INSPECTION [L3]

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Note

•  Before performing the following inspection, make sure to follow the troubleshooting flowchart. (See FOREWORD [L3].)

A/F Sensor 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)

―  A/F sensor 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 A/F sensor current (PID: O2S11) is 0.25 mA or more while decelerating as shown in the figure.

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•  If not within the specification, inspect the A/F sensor for an open or short circuit. (See A/F Sensor Circuit Open/Short Inspection.) Then if there is no malfunction in the wiring harness, replace the A/F sensor.

A/F Sensor Heater Resistance Inspection

1.  Disconnect the A/F sensor connector.

2.  Measure the resistance between A/F sensor terminals A and B.

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•  If not within the specification, replace the A/F sensor.

A/F Sensor Circuit Open/Short Inspection

1.  Disconnect the PCM connector.

2.  Disconnect the A/F sensor connector.

3.  Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

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―  A/F sensor terminal B and PCM terminal 2AD

―  A/F sensor terminal D and PCM terminal 2AC

―  A/F sensor terminal F and PCM terminal 2Z

―  A/F sensor terminal B and body ground

―  A/F sensor terminal B and power supply

―  A/F sensor terminal D and body ground

―  A/F sensor terminal D and power supply

―  A/F sensor terminal F and body ground

―  A/F sensor terminal F and power supply

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)

―  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 HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the HO2S voltage (PID: O2S12) is 0.3 V or less while decelerating as shown in the figure.

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•  If not within the specification, inspect the HO2S for an open or short circuit. (See HO2S Circuit Open/Short Inspection.) Then if there is no malfunction in the wiring harness, replace the HO2S.

HO2S Circuit Open/Short Inspection

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1.  Disconnect the PCM connector.

2.  Disconnect the HO2S connector.

3.  Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

―  HO2S terminal A and PCM terminal 2AH

―  HO2S terminal B and PCM terminal 2AA

―  HO2S terminal A and body ground

―  HO2S terminal A and power supply

―  HO2S terminal B and power supply

HO2S Heater Resistance Inspection

1.  Disconnect the HO2S connector.

2.  Measure the HO2S resistance between terminals C and D.

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•  If not within the specification, replace the HO2S.

HO2S Circuit Open/Short Inspection (heater)

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1.  Disconnect the PCM connector.

2.  Disconnect the HO2S connector.

3.  Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

―  HO2S terminal C and ignition switch

―  HO2S terminal D and PCM terminal 2C

―  HO2S terminal C and body ground

―  HO2S terminal D and power supply

―  HO2S terminal D and body ground