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Component Tests and General Diagnostics

HEATED OXYGEN SENSOR (HO2S) INSPECTION[LF, L3]

California Emission Regulation Applicable 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 M-MDS, monitor the following:
- Vehicle speed (PID: VSS)
- Engine speed (PID: RPM)
- Front HO2S 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 front HO2S current (PID: O2S11) 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 H02S heater resistance inspection
1. Disconnect the front HO2S connector.




2. Measure the resistance between front H02S terminals C and D.
- If not within the specification, replace the front H02S.

Front HO2S heater resistance : 1 - 10 ohms [20 °C {68 °F}]

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 2Z
- Front HO2S terminal C and PCM terminal 2BG
- Front HO2S terminal D and main relay terminal A

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 C and body ground
- Front HO2S terminal C and power supply
- Front HO2S terminal D and body ground

Middle/rear H02S voltage 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)
- Middle/rear HO2S voltage (PID: O2S12/O2S13)

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: O2S12/O2S13) 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
- Rear HO2S terminal A and PCM terminal 2Q
- Middle/rear HO2S terminal B and PCM terminal 2AY

Short circuit
- If there is continuity, there is a short circuit. Repair or replace the wiring harness.
- Middle/rear HO2S terminal A and body ground
- 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 H02S 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/rear HO2S terminal C and main relay A
- Middle HO2S terminal D and PCM terminal 2BF
- 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 ground
- Middle/rear HO2S terminal D and power supply
- Middle/rear HO2S terminal D and body ground

Except for California Emission Regulation Applicable Model

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

Front HO2S current 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)
- Front HO2S 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 front HO2S current (PID: O2S11) 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 H02S connector.




2. Measure the resistance between front HO2S terminals C and D.
- If not within the specification, replace the front H02S.

Front H02S heater resistance : 1 - 10 ohms [20 °C {68 °F}

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 main relay terminal A
- Front HO2S terminal B and PCM terminal 2AD
- Front HO2S terminal D and PCM terminal 2AC
- Front HO2S terminal E and PCM terminal 2BG*1,2G*2
- Front HO2S terminal F and PCM terminal 2Z

Short circuit
- If there is continuity in the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
- FrontH02S terminal A and body ground
- FrontHO2S terminal B and body ground
- FrontH02S terminal B and power supply
- FrontHO2S terminal D and body ground
- FrontH02S terminal D and power supply
- FrontH02S terminal E and body ground
- FrontHO2S terminal E and power supply
*1: LF MTX, L3
*2: LF ATX

Rear H02S voltage 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)
- Rear HO2S voltage (PID: O2S12)

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: O2S12) 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 01-40A-64 Rear HO2S circuit open/short inspection (sensor).) Then if there is no malfunction in the wiring harness, replace the rear HO2S.




Rear H02S 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.
- Rear HO2S terminal A and PCM terminal 2Q*1,2AH*2
- Rear HO2S terminal B and PCM terminal2P*\2AA*2

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
*1 : LF MTX, L3
*2 :LFATX

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 rear HO2S.

Rear HO2S heater resistance : 2 - 50 ohms







Rear H02S 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.
- Rear HO2S terminal C and main relay terminal A
- Rear HO2S terminal D and PCM terminal 2BE*1,2C*2

Short circuit
- If there is no continuity, there is a short circuit. Repair or replace the wiring harness.
Front and rear
- Rear HO2S terminal C and body ground
- Rear HO2S terminal D and power supply
- Rear HO2S terminal D and body ground

*1 : LF MTX, L3
*2 :LFATX
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