P0137

Schematic:

CIRCUIT DESCRIPTION
The PCM supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.

The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored H028 voltage samples taken within each sample period and determines if majority of the samples are out of the operating range.

The PCM monitors the HO2S voltage for being fixed below a predetermined voltage. If the PCM detects the voltage is below a predetermined voltage, this DTC sets.

CONDITIONS FOR RUNNING THE DTC

Criteria 1
^ DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0200, P0335, P0336, P0351-P0358, P1258 not set.
^ The ignition voltage is more than 9.0 volts.
^ The fuel system is operating in Closed Loop.
^ The AIR, EGR, and the Catalyst diagnostics are not active.
^ The fuel trim learn is enabled.
^ The TP sensor angle is between 2-70 percent.

OR

Criteria 2
^ DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0200, P0335, P0336, P0351-P0358, P1258 not set.
^ The ignition voltage is more than 9.0 volts.
^ The AIR, EGR, and the Catalyst diagnostics are not active.
^ The Power Enrichment mode is enabled for more than 1.0 second.

CONDITIONS FOR SETTING THE DTC

Criteria 1
^ The HO2S signal voltage remains below 80 mV.
^ The Criteria 1 conditions are present for 80 seconds.

OR

Criteria 2
^ The HO2S signal voltage remains below 420 mV.
^ The Criteria 2 conditions are present for 10 seconds during the Power Enrichment mode.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and tails.
^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM turns the Malfunction Indicator Lamp (MIL) OFF after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A last test failed (current DTC) clears when the diagnostic runs and does not fail.
^ A History DTC clears after 40 consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
^ Use a scan tool in order to clear the MIL/DTC.

DIAGNOSTIC AIDS

IMPORTANT:
^ Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminant intrusion into the PCM.
^ For any test that requires probing the PCM or component harness connectors, use the J 35616-A connector test adapter kit. Using this kit prevents any damage to the harness connector terminals. Refer to Using Connector Test Adapters in Diagrams.

The PCM sets this DTC when the vehicle runs out of fuel.
^ Heated Oxygen Sensor (HO2S) wire: Sensor pigtail may be in contact with the exhaust manifold or the exhaust system.
^ An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Heated Oxygen Sensor (HO2S) Wiring Repairs in Diagrams.
^ Inspect for an intermittent ground in the signal wire between the connector and the sensor.
^ Lean injector(s): Perform the Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 or Fuel Injector Balance Test with Special Tool. Component Tests and General Diagnostics Component Tests and General Diagnostics
^ Fuel contamination: Water near the in-tank fuel pump inlet can be delivered to the injectors. Refer to Alcohol/Contaminants-In-Fuel Diagnosis. The water causes a lean exhaust and can set a DTC. Testing and Inspection
^ Fuel pressure: System will be lean if fuel pressure is low. Refer to Fuel System Diagnosis. Component Tests and General Diagnostics
^ Exhaust leaks: An exhaust leak near the HO2S can cause a lean condition. Refer to Exhaust Leakage in Engine Exhaust.

Vacuum or crankcase leaks can cause a lean condition.

If the above are OK, the HO2S may be at fault.
For an intermittent condition, refer to Symptoms. Symptom Related Diagnostic Procedures

TEST DESCRIPTION

Steps 1 - 7:

Steps 8 - 9:

The numbers below refer to the step numbers on the diagnostic table.
2. If the HO2S voltage is fixed well below 200 mV, this indicates a short to battery ground or chassis ground. If the voltage is fixed near or above 200 mV, this indicates a short to a PCM ground. When the HO2S voltage is fixed near 200 mV, indicates the DTC set when the fuel system was in a Power Enrichment mode of operation. This DTC sets if the HO2S voltage is less than 420 mV during a Power Enrichment mode of operation.
The engine must be at the normal operating temperature before performing this test.
3. Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you can not duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that the PCM recorded. This isolates when the DTC failed.
4. Lower the exhaust system to gain sufficient access to the HO2S and/or the HO2S connector if necessary. Disconnecting the HO2S should cause the HO2S voltage to display a bias voltage. A voltage staying near 0.0 volts indicates the low circuit is open, or the high circuit is open or grounded.
5. Disconnecting the PCM allows using a DMM in order in order to test continuity of the circuits. This aids in locating an open or shorted circuit.