Air Fuel Ratio (A/F) Sensor Inspection

AIR FUEL RATIO (A/F) SENSOR INSPECTION [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.

- If not within the specification, inspect the A/F sensor for an open or short circuit. Then if there is no malfunction in the wiring harness, 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)

Open circuit
- If there is no continuity, there is an open circuit. Repair or replace the wiring harness.

- 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

Short circuit
- If there is continuity, there is a short circuit. Repair or replace the wiring harness.

- A/F sensor terminal B and body ground
- A/F sensor terminal B and power supply
- A/F sensor terminal D and power supply
- A/F sensor terminal D and body ground
- A/F sensor terminal F and power supply
- A/F sensor terminal F and body ground

A/F Sensor Heater Resistance Inspection

1. Disconnect the A/F sensor connector.

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

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

A/F sensor heater resistance
- 1-10 ohms

A/F Sensor Heater Circuit Open/short Inspection