Inspection Procedure

INSPECTION PROCEDURE

1. Check for open and short in harness and connector between ECM and Heated Oxygen Sensor
- If OK proceed to step 2.
- If not OK repair or replace harness or connector.
2. Check for Heated Oxygen Sensor data.
- Remove the fuse cover on the instrument panel.





- Connect the OBDII scan tool or LEXUS hand-held tester to the Data Link Connector 3.
- Warm up engine to normal operating temperature.
- Read the heated oxygen sensor output voltage and short-term fuel trim (Read the values for the same bank).

Pattern 1:
Heated Oxygen Sensor Output voltage indicates lean condition (changes at 0.55 volts or less): Short-term fuel trim changes at about +20%.

Pattern 2:
Heated Oxygen Sensor Output voltage indicates rich condition (changes at 0.4 volts or more): Short-term fuel trim changes at about -20%.

- If not OK proceed to step 3.
- If OK check fuel trim system.
3. Check the output voltage of Heated Oxygen Sensor during idling.
- Warm up the Heated Oxygen Sensor with the engine at 2,500 rpm for approximately 90 seconds.





- Use the OBDII scan tool or LEXUS hand-held tester read the output voltage of the Heated Oxygen Sensor during idling.

Heated oxygen sensor output voltage should alternate repeatedly between approximately 0.15 volts and approximately 0.7 volts.

- If OK perform confirmation driving pattern.
- If not OK replace Heated Oxygen Sensor