Heated Oxygen Sensor (HO2S) Inspection
HEATED OXYGEN SENSOR (HO2S) INSPECTION [MZI-3.7]
NOTE:
- Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart. Description and Operation
HO2S Inspection
1. Connect the M-MDS to the DLC-2.
2. Warm up the engine to normal operating temperature.
3. Access the following PIDs using the M-MDS. On-Board Diagnostic Test
- VSS (Vehicle speed)
- RPM (Engine speed)
- O2S12, O2S22 (HO2S output voltage)
4. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 rpm or more.
5. Verify that the HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the HO2S output voltage (PID: O2S12, O2S22) 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.
- Then if there is no malfunction in the wiring harness, replace the HO2S. Heated Oxygen Sensor (HO2S) Removal/Installation
HO2S Heater Inspection
1. Disconnect the negative battery cable. Removal and Replacement
2. Disconnect the HO2S connector.
3. Measure the resistance between HO2S terminals A and C.
- If it is not within the specification, replace the HO2S. Heated Oxygen Sensor (HO2S) Removal/Installation
- If the monitor item status/specification (reference) is not within the specification, even though the resistance is within the specification, perform the "Circuit Open/Short Inspection".
HO2S heater resistance
- 2-50 ohms
Circuit Open/Short Inspection
1. Disconnect the negative battery cable. Removal and Replacement
2. Disconnect the HO2S connector.
3. Disconnect the PCM connector.
4. Inspect the following wiring harness for open or short. (Continuity inspection)
Open circuit
- If there is no continuity, the circuit is open. Repair or replace the wiring harness.
- HO2S (LH) terminal A and PCM terminal 3AM
- HO2S (LH) terminal B and PCM terminal 3AB
- HO2S (LH) terminal C and main relay No.1 terminal D
- HO2S (LH) terminal D and PCM terminal 3X
- HO2S (RH) terminal A and PCM terminal 3N
- HO2S (RH) terminal B and PCM terminal 3Z
- HO2S (RH) terminal C and main relay No.1 terminal D
- HO2S (RH) terminal D and PCM terminal 3X
Short circuit
- If there is continuity, the circuit is shorted. Repair or replace the wiring harness.
- HO2S (LH)/(RH) terminal A and power supply
- HO2S (LH)/(RH) terminal A and body ground
- HO2S (LH)/(RH) terminal B and power supply
- HO2S (LH)/(RH) terminal B and body ground
- HO2S (LH)/(RH) terminal C and body ground
- HO2S (LH)/(RH) terminal D and power supply