AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) INSPECTION [L3 Turbo]
AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) INSPECTION [L3 Turbo]
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Note
• Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart. (See HOW TO USE THIS MANUAL.)
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 2B and 2D.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)
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Open circuit
• If there is no continuity in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness.
― A/F sensor terminal 1A and PCM terminal 2AD
― A/F sensor terminal 1B and PCM terminal 2AC
― A/F sensor terminal 1C and PCM terminal 2Z
― A/F sensor terminal 2A and PCM terminal 2M
― A/F sensor terminal 2B and main relay terminal A
― A/F sensor terminal 2C and PCM terminal 2Y
― A/F sensor terminal 2D and PCM terminal 2C
Short circuit
• If there is continuity in the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
― A/F sensor terminal 1A and body ground
― A/F sensor terminal 1A and power supply
― A/F sensor terminal 1B and body ground
― A/F sensor terminal 1B and power supply
― A/F sensor terminal 1C and body ground
― A/F sensor terminal 1C and power supply
― A/F sensor terminal 2A and power supply
― A/F sensor terminal 2B and body ground
― A/F sensor terminal 2C and body ground
― A/F sensor terminal 2C and power supply
― A/F sensor terminal 2D and body ground
― A/F sensor terminal 2D 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)
Open circuit
• If there is no continuity, there is an open circuit. Repair or replace the wiring harness.
― HO2S terminal A and PCM terminal 2Q
― HO2S terminal B and PCM terminal 1BC
Short circuit
• If there is continuity, there is a short circuit. Repair or replace the wiring harness.
― 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 heater resistance
2—50 ohms
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 check)
Open circuit
• If there is no continuity, there is an open circuit. Repair or replace the wiring harness.
― HO2S terminal C and ignition switch
― 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.
