P0137
DTC P0137: Secondary HO2S (Sensor 2) Circuit Low Voltage1. Reset the ECM/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 with the scan tool or the HDS.
Does the voltage stay at 0.3 V or less?
YES - Go to step 4.
NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at C204 (located under the right side of the dash), C102 (located under the under-hood fuse/relay box) the Secondary HO2S (Sensor 2), and the ECM/PCM.
4. Turn the ignition switch OFF.
5. Disconnect the Secondary HO2S (Sensor 2) 4P connector.
6. Start the engine.
7. Check the Secondary HO2S (Sensor 2) output voltage with the scan tool or the HDS.
Does the voltage stay at 0.3 V or less?
YES - Go to step 8.
NO - Replace the Secondary HO2S (Sensor 2).
8. Turn the ignition switch OFF.
9. Disconnect ECM/PCM connector A (32P).
10. Check for continuity between Secondary HO2S (Sensor 2) 4P connector terminal No.2 and body ground.
Is there continuity?
YES - Repair short in the wire between the ECM/PCM (E2) and the Secondary HO2S (Sensor 2).
NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.