Operation CHARM: Car repair manuals for everyone.
Home >> Mazda >> 2006 >> Mazdaspeed6 L4-2.3L Turbo >> Repair and Diagnosis >> Powertrain Management >> Sensors and Switches - Powertrain Management >> Sensors and Switches - Computers and Control Systems >> Oxygen Sensor >> Testing and Inspection >> Component Tests and General Diagnostics

Component Tests and General Diagnostics

HEATED OXYGEN SENSOR (HO2S) INSPECTION [L3 WITH TC]

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

Front HO2S 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)
- Front HO2S current (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 current (PID: 02S11) is 0.25 mA or more 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 heater resistance inspection

1. Disconnect the front HO2S connector.




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

Front HO2S heater resistance 1-10 ohms

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 in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness.
- Front HO2S terminal 1A and PCM terminal 2D
- Front HO2S terminal 1B and PCM terminal 2G
- Front HO2S terminal 1C and PCM terminal 2J
- Front HO2S terminal 2A and PCM terminal 2H
- Front HO2S terminal 2B and main relay terminal C
- Front HO2S terminal 2C and PCM terminal 2M
- Front HO2S terminal 2D and PCM terminal 4AD

Short circuit
- If there is continuity in the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
- Front HO2S terminal 1A and body ground
- Front HO2S terminal 1A and power supply
- Front HO2S terminal 1 B and body ground
- Front HO2S terminal 1 B and power supply
- Front HO2S terminal 1C and body ground
- Front HO2S terminal 1C and power supply
- Front HO2S terminal 2A and power supply
- Front HO2S terminal 2B and body ground
- Front HO2S terminal 2C and body ground
- Front HO2S terminal 2C and power supply
- Front HO2S terminal 2D and body ground
- Front HO2S terminal 2D and power supply

Rear 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)
- Rear HO2S voltage (PID: 02S12)

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 rear HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the rear HO2S voltage (PID: 02S12) 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 Rear HO2S circuit open/short inspection (sensor).) Then if there is no malfunction in the wiring harness, replace the rear HO2S.

Rear HO2S circuit open/short inspection (sensor)

1. Disconnect the PCM connector.
2. Disconnect the rear HO2S connector.







3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspect)

Open circuit
- If there is no continuity, there is an open circuit. Repair or replace the wiring harness
- Rear HO2S terminal A and PCM terminal 1Y
- Rear HO2S terminal B and PCM terminal 2H

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

Rear HO2S heater resistance inspection

1. Disconnect the rear HO2S connector.
2. Measure the rear HO2S resistance between terminals C and D.
- If not within the specification, replace the HO2S.

Rear HO2S heater resistance 2-50 ohms

Rear HO2S circuit open/short inspection (heater)

1. Disconnect the PCM connector.




2. Disconnect the rear 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.
- Rear HO2S terminal C and ignition switch
- Rear HO2S terminal D and PCM terminal 4Z

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