HEATED OXYGEN SENSOR (HO2S) INSPECTION

Note

• Perform the following inspection according to the DATA MONITOR function (indicated by the monitor item from here onwards).

HO2S Voltage Inspection

1. Warm up the engine to normal operating temperature.

2. Disconnect the HO2S connector.

3. Connect the positive battery terminal of the tester to terminal A, and the negative battery terminal to terminal B, then measure the voltage.

4. Run the engine at 3,000 rpm until the voltage indicates approx. 0.5-0.7 V.

5. Verify that the voltage is as indicated in the table when the engine is raced repeatedly.

• If not within the specification, replace the HO2S_.

• If the monitor item condition/specification (reference) is not within the specification, even though the voltage is within the specification, carry out the "Circuit Open/Short Inspection".

Voltage

Engine condition	Voltage (V)
Decelerated	0-0.5
Accelerated	0.5-1.0

Circuit Open/Short Inspection

1. Inspect the following wiring harnesses for an open or short circuit. (Continuity check)

Open circuit

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

- HO2S terminal A and PCM terminal 2AI

- HO2S terminal B and PCM terminal 2AX

Short circuit

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

- HO2S terminal A and power supply

- HO2S terminal A and body GND

- HO2S terminal B and power supply

- HO2S terminal B and body GND

HO2S Heater Resistance Inspection

1. Disconnect the negative battery cable.

2. Disconnect the HO2S connector.

3. Inspect the resistance between terminals C and D.

• If not within the specification, replace the HO2S_.

5.0-6.8 ohms (when HO2S is cold)

Circuit Open/Short Inspection

1. Inspect the following wiring harnesses for an open or short circuit. (Continuity check)

Open circuit

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

- HO2S terminal C and PCM terminal 2T

- HO2S terminal D and PCM terminal 2AM

Short circuit

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

- HO2S terminal C and body GND

- HO2S terminal D and power supply

- HO2S terminal D and body GND