Operation CHARM: Car repair manuals for everyone.
Home >> Mazda >> 2006 >> 5 L4-2.3L >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Sensors and Switches - Computers and Control Systems >> Oxygen Sensor >> Testing and Inspection >> Component Tests and General Diagnostics >> Front Heated Oxygen Sensor (HO2S) Inspection

Front Heated Oxygen Sensor (HO2S) Inspection

FRONT HEATED OXYGEN SENSOR (HO2S) INSPECTION [L3]

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

Front HO2S voltage 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)
- Front HO2S voltage (PID: 02S11)

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 front HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the front HO2S voltage (PID: 02S11) is 0.3 V or less while decelerating as shown in the figure.
- If not within the specification, inspect the HO2S for an open or short circuit. (See Front HO2S circuit open/short inspection (sensor).) Then if there is no malfunction in the wiring harness, replace the front HO2S.

Front HO2S circuit open/short inspection (sensor)

1. Disconnect the PCM connector.




2. Disconnect the front HO2S 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.
- HO2S terminal A and PCM terminal 2AG
- HO2S terminal B and PCM terminal 2AA

Short circuit
- If there is continuity, there is a short circuit. Repair or replace the wiring harness,
- HO2S terminal A and body ground
- HO2S terminal A and power supply
- HO2S terminal B and power supply

Front HO2S heater resistance inspection

1. Disconnect the front HO2S connector.




2. Measure the resistance between front HO2S terminals C and D.
- If not within the specification, replace the front HO2S.

Front HO2S heater resistance: 2-50 Ohms

Front HO2S heater circuit open/short inspection (heater)

1. Disconnect the PCM connector.
2. Disconnect the front HO2S 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.
- HO2S terminal D and PCM terminal 2G

Short circuit
- If there is no continuity, there is a short circuit. Repair or replace the wiring harness.
- HO2S terminal C and body ground
- HO2S terminal D and power supply
- HO2S terminal D and body ground
pro multis · About Operation CHARM