Rear Heated Oxygen Sensor (HO2S) Inspection

REAR 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

Rear Heated Oxygen Sensor (HO2S) 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, O2S22)

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, O2S22) is 0.3 V is or less while decelerating as shown in the figure.






- If not within the specification, inspect the rear HO2S for an open or short circuit. Then if there is no malfunction in the wiring harness, replace the rear HO2S. Rear Heated Oxygen Sensor (HO2S) Removal/Installation

HO2S Heater Resistance Inspection

1. Disconnect the HO2S connector.

2. Measure the resistance between HO2S terminals C and A.






- If it is not within the specification, replace the HO2S. Rear 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
- 3-30 ohms

Circuit Open/Short Inspection

1. Disconnect the PCM connector. Service and Repair

2. Inspect the following wiring harness for open or short (continuity check).






Open circuit

- If there is no continuity, the circuit is open. Repair or replace the harness.

- HO2S (RH) terminal A and PCM terminal 2AS
- HO2S (RH) terminal B and PCM terminal 2BG
- HO2S (RH) terminal C and main relay No.2 terminal D
- HO2S (RH) terminal D and PCM terminal 2AL
- HO2S (LH) terminal A and PCM terminal 2AO
- HO2S (LH) terminal B and PCM terminal 2BC
- HO2S (LH) terminal C and main relay No.2 terminal D
- HO2S (LH) terminal D and PCM terminal 2AL

Short circuit

- If there is continuity, the circuit is shorted. Repair or replace the harness.

- HO2S (RH) terminal A and power supply
- HO2S (RH) terminal A and body ground
- HO2S (RH) terminal B and power supply
- HO2S (RH) terminal B and body ground
- HO2S (RH) terminal C and body ground
- HO2S (RH) terminal D and power supply
- HO2S (LH) terminal A and power supply
- HO2S (LH) terminal A and body ground
- HO2S (LH) terminal B and power supply
- HO2S (LH) terminal B and body ground
- HO2S (LH) terminal C and body ground
- HO2S (LH) terminal D and power supply