Mazda 2: Air Fuel Ratio (A/F) Sensor

AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION

WARNING:

• A hot engine and exhaust system can cause severe burns. Turn off the engine and wait until they are cool before removing the exhaust system.

1. Disconnect the negative battery cable.

2. Remove the air cleaner cover. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION).

3. Disconnect the A/F sensor connector.

4. Remove the A/F sensor using the SST.

5. Install in the reverse order of removal.

AIR FUEL RATIO (A/F) SENSOR INSPECTION

A/F Sensor 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 as specified, replace the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION).

A/F Sensor Heater Inspection

1. Disconnect the A/F sensor connector.

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

• If not as specified, replace the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION).

A/F sensor heater resistance

• 1-10 ohms

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