Diagnosis & Repair
WARNING: This page is about a different car, the 2003 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.
- Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If only DTC P0420 or P0430 is displayed, go to next step. If other codes are displayed, diagnose and repair those codes first and retest.
- Check for exhaust leaks. Repair as necessary. If exhaust system is okay, check heated oxygen sensor circuits. See DTC P0130, DTC P0150, DTC P2195, DTC P2196, DTC P2197 OR DTC P2198 test. Repair as necessary. If no problems are indicated, go to next step.
- Check heated oxygen sensor. Disconnect the H9, H10, H15 and H16 heated oxygen sensor connectors. Measure the resistance between the terminals of the connectors (component side). See Fig 1. See HEATED OXYGEN SENSOR RESISTANCE table. Replace appropriate oxygen sensor as necessary. If oxygen sensor circuits are okay, replace appropriate catalytic converter and retest.HEATED OXYGEN SENSOR RESISTANCE
Terminal No. °F (°C) Ohms Bank 1 Sensor 1 & Bank 2 Sensor 1 1-4 68 (20) 11-16 1-4 1472 (800) 23-32 Bank 1 Sensor 2 & Bank 2 Sensor 2 2-3 68 (20) 11-16 2-3 1472 (800) 23-32