Engine Controls - MIL ON/DTC's P0138/P0158
T-SB-0001-10January 7, 2010
MIL "ON" DTC P0138 and/or P0158 Diagnostic Tips
Service Category
Engine/Hybrid System
Section
Engine Control
Market
USA
Applicability
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.
^ Refer to TSB No. "Engine Bank I and Bank 2 A/F and 02 Identification" before proceeding to confirm diagnosis is performed on the correct engine bank.
^ Before proceeding, check for any other applicable TSB(s). Do not apply this diagnostic procedure if there is an existing TSB for A/F or 02 sensor DTC(s).
Warranty Information
Diagnostic 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 O2S B#S2 = O.70~0.90V?
^ YES - Replace the appropriate bank Air Fuel Ratio Sensor ONLY (NOT O2 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 P01381P0158 diagnosis:
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:
If the MIL "ON" condition continues to occur after this procedure, refer to the Repair Manual for further diagnostic procedures and specifications.