Except California Emission Regulation Applicable ATX Model
HEATED OXYGEN SENSOR (HO2S) INSPECTIONExcept for California Emission Regulation Applicable ATX Model
NOTE: Before performing the following inspection, troubleshooting flowchart. make sure to follow the procedure as indicated in the
Front/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)
- Front/rear HO2S voltage (PID: O2S11/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 front/rear HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the front/rear HO2S voltage (PID: O2S11/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 Front/rear HO2S circuit open/short inspection (sensor).) Then if there is no malfunction in the wiring harness, replace the front/rear HO2S.
Front/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.
- Front HO2S terminal A and PCM terminal 1AB
- Front HO2S terminal B and PCM terminal 2H
- 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.
- Front/rear HO2S terminal A and body GND
- Front/rear HO2S terminal A and power supply
- Front/rear HO2S terminal B and power supply
Front/rear HO2S heater resistance inspection
1. Disconnect the front/rear HO2S connector.
2. Measure the resistance between the front/rear HO2S terminals C and D.
- If not within the specification, replace the HO2S.
Front HO2S heater resistance
2 - 20 ohms
Rear HO2S heater resistance
2 - 50 ohms
Front/rear HO2S heater 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.
- Front HO2S terminal C and ignition switch
- Front HO2S terminal D and PCM terminal 4A
- Rear HO2S terminal C and ignition switch
- Rear HO2S terminal D and PCM terminal 4D
Short circuit
- If there is no continuity, there is a short circuit. Repair or replace the wiring harness.
Front and rear
- Front/rear HO2S terminal C and body GND
- Front/rear HO2S terminal D and power supply
- Front/rear HO2S terminal D and body GND