AIR FUEL RATIO (A/F) SENSOR INSPECTION [L8, LF]

Note

• Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart. (See Troubleshooting Procedure.)

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.

• 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. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [L8, LF].)

A/F Sensor Heater Resistance Inspection

1. Disconnect the A/F sensor connector.

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

• If not within the specification, replace the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [L8, LF].)

1-10 ohms

A/F Sensor Circuit open/short Inspection

1. Disconnect the PCM connector. (See PCM REMOVAL/INSTALLATION [L8, LF].)

2. Disconnect the A/F sensor connector.

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

- A/F sensor terminal A and PCM terminal 2AD

- A/F sensor terminal B and PCM terminal 2Z

- A/F sensor terminal C ignition relay

- A/F sensor terminal D and PCM terminal 2BG

- A/F sensor terminal A and power supply

- A/F sensor terminal A and body ground

- A/F sensor terminal B and power supply

- A/F sensor terminal B and body ground

- A/F sensor terminal C and body ground

- A/F sensor terminal D and power supply

- A/F sensor terminal D and body ground