P0138
DTC P0138: Secondary HO2S (Sensor 2) Circuit High Voltage1. Reset the PCM.
2. Start the engine. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on.
3. Check the secondary HO2S (Sensor 2) output voltage at 3,000 rpm with a scan tool or the HDS.
Is there 1.0 V or more?
YES - Go to step 4.
NO - Intermittent failure. The system is OK at this time. Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and at the PCM.
4. Turn the ignition switch OFF.
5. Disconnect the secondary HO2S (Sensor 2) 4P connector.
6. Connect secondary HO2S (Sensor 2) 4P connector terminals No.1 and No.2 with a jumper wire.
7. Turn the ignition switch ON (II).
8. Check the secondary HO2S (Sensor 2) output voltage with a scan tool or the HDS.
Is there 1.0 V or more?
YES - Go to step 9.
NO - Replace the secondary HO2S (Sensor 2).
9. Turn the ignition switch OFF.
10. Connect PCM connector terminals A10 and A25 with a jumper wire.
11. Turn the ignition switch ON (II).
12. Check the secondary HO2S (Sensor 2) output voltage with a scan tool or the HDS.
Is there 1.0 V or more?
YES - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
NO - Repair open in the wire between the PCM (A10, A25) and the secondary HO2S (Sensor 2).