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 any other codes are displayed other than DTC P0136 or P0156, diagnose and repair those codes first. If only DTC P0136 or P0156 are displayed, go to next step.
- Disconnect the H15 and H16 heated oxygen sensor connectors. Disconnect the E5 ECM connector. See Fig 1 and Fig 2
. Check continuity between the wire harness side connectors. See HO2S/ECM CONTINUITY CHECK table. Repair wiring as necessary. If wiring harness is okay, go to next step.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
HO2S/ECM CONTINUITY CHECKTerminals No. Specification OX (H15-4) - OXL2 (E5-28) Continuity HT (H15-2) - HTL2 (E5-7) Continuity OX (H16-4) - OXR2 (E5-17) Continuity HT (H16-2) - HTR2 (E5-8) Continuity OX (H15-4) Or OXL2 (E5-28) - E1 (E3-7) No Continuity HT (H15-2) Or HTL2 (E5-7) - E1 (E3-7) No Continuity OX (H16-4) Or OXR2 (E5-17) - E1 (E3-7) No Continuity HT (H16-2) Or HTR2 (E5-8) - E1 (E3-7) No Continuity - Connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Start and warm engine to normal operating temperature. Monitor bank 1 and 2, sensor 2. Raise engine speed to 2500 RPM for 3 minutes. Return engine to idle. Quickly raise engine speed to 4000 RPM 3 times. Voltage should fluctuate from .4 volt or less to .5 volt or more. If voltage responds correctly, check wiring harness connections. Problem may be intermittent. If voltage does not respond correctly, replace appropriate oxygen sensor and retest.