P0137
DTC P0137CIRCUIT DESCRIPTION
Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the vehicle is first started, the (PCM) operates in an Open Loop mode, ignoring the HO2S signal voltage when calculating the air-to-fuel ratio. The PCM supplies the HO2S with a reference or bias voltage of about 450 mV. The HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage once the sensor reaches operating temperature. A high HO2S voltage output indicates a rich fuel mixture. A low HO2S voltage output indicates a lean mixture. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature and provide an accurate voltage signal. The HO2S 2 is used for post catalyst monitoring. If the PCM detects that the HO2S 2 voltage remains below a calibrated value for an excessive amount of time, DTC P0137 will set.
The HO2S 2 has the following circuits:
- An HO2S 2 high signal circuit
- An HO2S 2 low signal circuit
- An HO2S 2 heater ignition 1 voltage circuit
- An HO2S 2 heater low control circuit
CONDITIONS FOR RUNNING THE DTC
- DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0442, P0443, P0446, P0449, P0455, P0496, P1106, P1107, P1111, P1112, P1114, P1115, P2135 are not set.
- The ignition voltage is more than 9 volts and less than 18 volts.
- DTCs P0136, P0401, and P0420 passed.
- The HO2S heater is not being commanded by the scan tool.
- The Loop Status parameter is closed.
- The ECT Sensor parameter is less than 131°C (268°F).
- The traction control is not active.
- The TP Indicated Angle parameter is between 4-40 percent.
- The TP Indicated Angle parameter is varying less than 4 percent.
CONDITIONS FOR SETTING THE DTC
The PCM detects that the HO2S 2 signal voltage remains below 78 mV during Closed Loop operation for more than 2 minutes.
ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.
TEST
