Air Fuel Ratio (A/F) Sensor Inspection

AIR FUEL RATIO (A/F) SENSOR INSPECTION [MZI-3.7]

NOTE:
- Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart. Description and Operation

A/F Sensor Inspection

1. Connect the M-MDS to the DLC-2.






2. Warm up the engine to normal operating temperature.

3. Drive the vehicle.

4. Release the accelerator pedal while the engine speed is at 3,000 rpm or more and verify that the following monitor items fluctuate as shown in the figure while the vehicle decelerates. On-Board Diagnostic Test






- VSS
- RPM
- O2S11, O2S21

- If not within the specification, replace the A/F sensor. Air Fuel Ratio (A/F) Sensor Removal/Installation

A/F Sensor Heater Inspection

1. Disconnect the negative battery cable. Removal and Replacement

2. Disconnect the A/F sensor connector.

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






- If it is not within the specification, replace the A/F sensor. Air Fuel Ratio (A/F) Sensor Removal/Installation
- 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".

A/F sensor heater resistance
- 1-10 ohms

Circuit Open/Short Inspection





1. Disconnect the negative battery cable. Removal and Replacement

2. Disconnect the A/F sensor connector.

3. Disconnect the PCM connector.

4. Inspect the following wiring harness for open or short. (Continuity inspection)

Open circuit

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

- A/F sensor (LH) terminal C and main relay No.1 terminal D
- A/F sensor (LH) terminal D and PCM terminal 2BF
- A/F sensor (LH) terminal E and PCM terminal 2E
- A/F sensor (LH) terminal F and PCM terminal 2AK
- A/F sensor (LH) terminal G and PCM terminal 2AO
- A/F sensor (LH) terminal H and PCM terminal 2AE
- A/F sensor (RH) terminal C and main relay No.1 terminal D
- A/F sensor (RH) terminal D and PCM terminal 2BD
- A/F sensor (RH) terminal E and PCM terminal 2J
- A/F sensor (RH) terminal F and PCM terminal 2AG
- A/F sensor (RH) terminal G and PCM terminal 2AS
- A/F sensor (RH) terminal H and PCM terminal 2AC

Short circuit

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

- A/F sensor (LH)/(RH) terminal C and body ground
- A/F sensor (LH)/(RH) terminal D and power supply
- A/F sensor (LH)/(RH) terminal D and body ground
- A/F sensor (LH)/(RH) terminal E and power supply
- A/F sensor (LH)/(RH) terminal F and power supply
- A/F sensor (LH)/(RH) terminal F and body ground
- A/F sensor (LH)/(RH) terminal G and power supply
- A/F sensor (LH)/(RH) terminal G and body ground
- A/F sensor (LH)/(RH) terminal H and power supply
- A/F sensor (LH)/(RH) terminal H and body ground