FRONT HEATED OXYGEN SENSOR (HO2S) INSPECTION

Note

• Before performing the following inspection, make sure to follow the troubleshooting flowchart. (See Troubleshooting Procedure.)

Front Heated Oxygen Sensor (HO2S) Current Inspection

1. Warm up the engine to normal operating temperature.

2. Using the WDS or equivalent, verify that the current of the front HO2S (WDS PID: O2S11) is as indicated in the table.

• If it cannot be verified even though the related harnesses have no malfunction, replace the front HO2S. (See FRONT HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION.)

Front HO2S current

Engine condition	Current (mA)
Accelerated	Positive value
Decelerated	Negative value

Front Heated Oxygen Sensor (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. (See FRONT HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION.)

Front HO2S heater resistance

2.16-2.90 ohms [20 °C {68 °F}]

Circuit Open/Short Inspection

1. Disconnect the PCM connector.

2. Disconnect the front HO2S connector.

3. Inspect the following wiring harnesses for 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 2B

– Front HO2S terminal B and PCM terminal 2C

– Front HO2S terminal C and main relay terminal C

– Front HO2S terminal D and PCM terminal 1V

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