FRONT HEATED OXYGEN SENSOR (HO2S) INSPECTION[AJ (3.0L Duratec)]

id0140a1804700

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 Heated Oxygen Sensor (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)

―  Front HO2S voltage (PID: O2S11, O2S21)

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 outputs a voltage of 0.6 V or more, one time or more, then verify that the front HO2S voltage (PID: O2S11, O2S21) is 0.3 V is or less while decelerating as shown in the figure.

atraaw00003393

•  If not within the specification, inspect the front HO2S for an open or short circuit. (See Front Heated Oxygen Sensor (HO2S) Voltage Inspection.) Then if there is no malfunction in the wiring harness, replace the front HO2S. (See FRONT HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION[AJ (3.0L Duratec)].)

HO2S Heater Resistance Inspection

1.  Disconnect the HO2S connector.

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

atraaw00000198

•  If it is not within the specification, replace the HO2S. (See FRONT HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION[AJ (3.0L Duratec)].)

•  If the monitor item status/specification (reference) is not within the specification, even though the resistance is within the specification, perform the “Circuit Open/Short Inspection”.

Circuit Open/Short Inspection

1.  Disconnect the PCM connector. (See PCM REMOVAL/INSTALLATION[AJ (3.0L Duratec)].)

2.  Inspect the following wiring harness for open or short (continuity check).

atraaw00001585

Open circuit

•  If there is no continuity, the circuit is open. Repair or replace the harness.

―  HO2S (RH) terminal A and PCM terminal 93

―  HO2S (RH) terminal B and PCM terminal 60

―  HO2S (RH) terminal C and main relay terminal B

―  HO2S (RH) terminal D and PCM terminal 31

―  HO2S (LH) terminal A and PCM terminal 94

―  HO2S (LH) terminal B and PCM terminal 87

―  HO2S (LH) terminal C and main relay terminal B

―  HO2S (LH) terminal D and PCM terminal 31

Short circuit

•  If there is continuity, the circuit is shorted. Repair or replace the harness.

―  HO2S (RH) terminal A and power supply

―  HO2S (RH) terminal A and body ground

―  HO2S (RH) terminal B and power supply

―  HO2S (RH) terminal B and body ground

―  HO2S (RH) terminal C and body ground

―  HO2S (RH) terminal D and power supply

―  HO2S (LH) terminal A and power supply

―  HO2S (LH) terminal A and body ground

―  HO2S (LH) terminal B and power supply

―  HO2S (LH) terminal B and body ground

―  HO2S (LH) terminal C and body ground

―  HO2S (LH) terminal D and power supply