Operation CHARM: Car repair manuals for everyone.
Home >> Mazda >> 2006 >> 6 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 >> California Emission Regulation Applicable ATX Model

California Emission Regulation Applicable ATX Model

HEATED OXYGEN SENSOR (HO2S) INSPECTION [L3]

California Emission Regulation Applicable ATX Model

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 C and D.
- 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 A and PCM terminal 2AD
- Front HO2S terminal B and PCM terminal 22
- Front HO2S terminal C and PCM terminal 2BG
- Front HO2S terminal D and ignition switch.

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 A and body ground
- Front HO2S terminal A and power supply
- Front HO2S terminal B and body ground
- Front HO2S terminal B and power supply
- Front HO2S terminal D and body ground

Middle/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)
- Middle/rear HO2S voltage (PID: 02S12/02S13)

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 middle/rear HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the middle/rear HO2S voltage (PID: 02S12/02S13) 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 Middle/rear HO2S circuit open/short inspection (sensor).) Then if there is no malfunction in the wiring harness, replace the middle/rear HO2S.

Middle/rear HO2S circuit open/short inspection (sensor)




1. Disconnect the PCM connector.
2. 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.
- Middle HO2S terminal A and PCM terminal 2R
- Middle HO2S terminal B and PCM terminal 1 BG
- Rear HO2S terminal A and PCM terminal 2Q
- Rear HO2S terminal B and PCM terminal 1BC

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

Middle/rear HO2S heater resistance inspection




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

Middle/rear HO2S heater resistance 2-50 ohms

Middle/rear HO2S circuit open/short inspection (heater)

1. Disconnect the PCM connector.




2. 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.
- Middle HO2S terminal C and ignition switch
- Middle HO2S terminal D and PCM terminal 2BF
- Rear HO2S terminal C and ignition switch
- Rear HO2S terminal D and PCM terminal 2BE

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