P0137

DTC P0137: HO2S Circuit Low Voltage Bank 1 Sensor 2

Wiring Diagram:

Circuit Description
The Engine Control Module (ECM) supplies a voltage of about 0.45 V between the ECM terminals K10 and K9. The Oxygen (O2) sensor varies the voltage within a range of about 1 V if the exhaust is rich, down to about 0.1 V if the exhaust is lean. The O2 sensor is like an open circuit and produces no voltage when it is below 300 degrees C (600 degrees F). An open O2 sensor circuit or a cold O2 sensor causes "Open Loop" operation.

Conditions for Setting the DTC
- No MAF, CKP, TP, CMP or fuel system faults exist.
- Ignition ON.
- Mass Air Flow (MAF) is greater than 12 kg/h.
- HO2S voltage is less than 0.02 V.
- Internal resistance of oxygen sensor is less than 20 Ohms.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM will record operating conditions at the time the diagnostic fail. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- The MIL will turn OFF at the end of 3 consecutive validation cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 warm up cycles without a fault.
- DTC(s) can be cleared by using the scan tool.

Diagnostic Aids
- Normal scan tool voltage varies between 0.1 and 0.9 V while in Closed Loop.
- Inspect the Oxygen (O2) sensor wire. The O2 sensor may be positioned incorrectly and contacting the exhaust manifold.
- Check for an intermittent ground in the wire between the O2 sensor and the engine control module.
- Perform an injector balance test to determine if a restricted fuel injector may be causing the lean condition.
- Vacuum of crankcase leaks will cause a lean running condition.
- An exhaust manifold gasket leak of a cracked exhaust manifold may cause outside air to be pulled into the exhaust and past the sensor.

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DTC Troubleshooting