P0137
DTC P0137: Secondary HO2S (Sensor 2) Circuit Low Voltage1. Reset the ECM with the HDS.
2. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on.
3. Check the HO2S S2 at 3,000 rpm in the DATA LIST with 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 the secondary HO2S (Sensor 2) and the ECM.
4. Turn the ignition switch OFF.
5. Disconnect the secondary HO2S (Sensor 2) 4P connector.
6. Start the engine.
7. Check the HO2S S2 in the DATA LIST with the HDS.
Does the voltage stay at 0.3 V or less?
YES - Go to step 8.
NO - Replace the secondary HO2S (Sensor 2), and the third HO2S (Sensor 3)*1.
* 1: 2002-2005 M/T models
8. Turn the ignition switch OFF.
9. Disconnect ECM connector C (31P).
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 (C31) and the secondary HO2S (Sensor 2).
NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.