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AIR FUEL RATIO (A/F) SENSOR INSPECTION [MZR-CD (RF Turbo)]

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  Note

  • Before performing the following inspection, make sure to follow the troubleshooting flowchart.

## A/F sensor current inspection

1. Warm up the engine to normal operating temperature.

2. Using the WDS or equivalent, 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 (sensor).) Then if there is no malfunction in the wiring harness, replace the front A/F sensor.

  - If there is no open/short circuit, replace the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [MZR-CD (RF Turbo)])

## 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 [MZR-CD (RF Turbo)].)

A/F sensor heater resistance

  1-10 ohms

## A/F sensor circuit open/short inspection (sensor)

1. Disconnect the PCM connector. (See PCM REMOVAL/INSTALLATION [MZR-CD (RF Turbo)])

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 in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness.

  - A/F sensor terminal A and PCM terminal 93
  - A/F sensor terminal B and PCM terminal 85
  - A/F sensor terminal C and PCM control relay terminal C
  - A/F sensor terminal D and PCM terminal 34

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