Mazda 3 Service Manual: Air Fuel Ratio (A/F) Sensor Inspection [Mzr 2.0, Mzr 2.5]

A/F Sensor Inspection

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

2. Switch the ignition to ON.

3. Warm up the engine to normal operating temperature.

4. Access the following PIDs using the M-MDS..

• VSS (Vehicle speed)

• RPM (Engine speed)

• O2S11 (A/F sensor output current)

5. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 rpm or more

.

6. Verify that the A/F sensor output 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..

A/F Sensor Heater Inspection

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. Remove the battery cover..

2. Disconnect the negative battery cable..

3. Remove the plug hole plate..

4. Remove the air cleaner assembly. (MZR 2.5).

5. Disconnect the A/F sensor connector.

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

• If not as specified, replace the A/F sensor..

A/F sensor heater resistance

• 1—10 ohms [normal temperature]