Engine Controls - MIL ON/DTC P0138/P0158 Diagnostic Tips
L-SB-0109-09Rev1
September 2, 2009
MIL "ON" DTC P0138 and/or P0158 Diagnostic Tips
Service Category
Engine/Hybrid System
Section
Engine Control
Market
USA
Applicability
TSIB REVISION NOTICE
^ December 23, 2009 Rev1:
^ The Introduction Note has been updated.
Any previous printed versions of this service bulletin should be discarded.
Introduction
Some vehicles may exhibit a MIL "ON" Diagnostic Trouble Code (DTC) P0138 and/or P0158 (Oxygen Sensor Circuit High Voltage Bank 1 or 2). In some instances a P2195 or P2197 (A/F Sensor Signal Stuck Lean) DTC may also be present. This condition may be caused by incorrect Air Fuel Ratio Sensor response. Additionally, a P0606 (ECM/PCM Processor) DTC may be present due to incorrect Oxygen Sensor operation. The following repair procedures should be used to properly diagnose and repair this condition.
NOTE
^ Refer to TSIB No. L-SB-0188-09, "Engine Bank 1 and Bank 2 A/F and 02 Identification" before proceeding to confirm diagnostic procedure is performed on the correct engine bank.
^ Before proceeding, check for any other applicable TSIB(s). Do not apply this diagnostic procedure if there is an existing TSIB for A/F or 02 sensor DTC(s).
Warranty Information
Diagnostic Procedure
For information on checking circuit open, short, or resistance test procedures please refer to the Technical Information System (TIS), applicable model and model year Repair Manual:
HINT
^ 2007 / 2010 ES 350:
General - Introduction - "How to Troubleshoot ECU Controlled Systems: Electronic Circuit Inspection Procedure"
^ 2008 / 2009 ES 350:
General - Identification - "How to Troubleshoot ECU Controlled Systems: Electronic Circuit Inspection Procedure"
^ 2007 / 2008 / 2009 / 2010 RX 350:
General - Introduction - "How to Troubleshoot ECU Controlled Systems: Electronic Circuit Inspection Procedure"
1. Check all DTCs.
Are DTC(s) other than P0138 or P0158 present?
Yes:
^ P2195 and/or P2197 DTC also present: Go to step 3.
^ P0606 DTC also present: Go to step 4.
No:
^ Go to step 2.
2. Check the A/F and 02 sensor values for the appropriate bank DTC Freeze Frame Data (FFD). Is the AFS Voltage B#S1 = 3.35~3.70V AND the 02S B#S2 = 0.70~0.90V?
Yes:
^ Replace the appropriate bank Air Fuel Ratio Sensor ONLY (NOT 02 Sensor) to correct the P0138 or P0158 DTC condition.
No:
^ Inspect the 02 B#S2 circuit for open short or high resistance. If no trouble is found refer to TIS applicable model and model year Repair Manual for P0138/P0158 diagnosis:
2007 / 2008 / 2009 / 2010 ES350:
Engine/Hybrid System - Engine Control - SFI System - "2GR-FE Engine Control System: SFI System: Diagnosis System"
^ 2007 / 2008 / 2009 / 2010 (to 08/2009) RX350:
Engine/Hybrid System - Engine Control - SFI System - "2GR-FE Engine Control System: SFI System: Diagnosis System"
3. Inspect Air Fuel Ratio Sensor for the appropriate bank.
Does the Air Fuel Ratio Sensor have an open or short on the A1A+ or A1A- wires?
Yes:
^ Repair the harness and revaluate the Air Fuel Ratio Sensor operation. Confirm the previous DTC(s) do not reset.
No:
^ Replace the applicable bank Air Fuel Ratio Sensor ONLY to correct the P2195/P0138 or P2197/P0158 DTC condition. Test drive the vehicle to confirm none of the previous DTC(s) reset.
4. Inspect Oxygen Sensor 2 Freeze Frame Data (FFD) values.
Is the 02S B#S2 voltage more than 1.10v and/or the 02S Impedance B#S2 more than 300 ohms when engine is at normal operating temperature?
Yes:
^ Inspect 02 B#S2 circuit for open short or high resistance. If no harness issues are found replace the appropriate bank 02 Sensor ONLY to correct the P0606 DTC.
No:
^ Follow the Repair Manual diagnostic procedure for P0138/P0158 DTC:
^ 2007 / 2008 / 2009 / 2010 ES 350:
Engine/Hybrid System - Engine Control - SFI System - "2GR-FE Engine Control System: SFI System: Diagnosis System"
2007 / 2008 / 2009 / 2010 (from 08/2009) RX350:
Engine/Hybrid System - Engine Control - SFI System - "2GR-FE Engine Control System: SFI System: Diagnosis System"
If the MIL "ON" condition continues to occur after this procedure, refer to the Repair Manual for further diagnostic procedures and specifications.