P1137

DTC P1137: HO2S Circuit Low Voltage During Power Enrichment Sensor 2

Wiring Diagram:

Circuit Description
The Heated Oxygen Sensor (HO2S) produces a voltage that varies between 100 - 900 mV under normal operating conditions. The Engine Control Module (ECM) produces a bias voltage on the HO2S signal circuit of 420 - 480 mV. The reference ground for the sensor is provided through the ECM. The ECM monitors the signal voltage to determine if the exhaust is lean or rich. The heated oxygen sensor voltage is high when the exhaust is rich, and low when the exhaust is lean. The ECM constantly monitors the HO2S signal during the Closed Loop operation. If the ECM detects an HO2S voltage that stays below a specified value during a power enrichment condition, the DTC will set.

Conditions for Setting the DTC
- Mass air flow is greater than 6 g/s.
- Ignition voltage is greater than 10 V.
- The engine is running for greater than 10 seconds.
- Power enrichment conditions are met.
- Coolant temperature is greater than 60 °C.
- HO2S filtered voltage is less than 0.3501 V.
- Air fuel ratio is less than 13.5 : 1.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM will record operating conditions at the time the diagnostic fails. 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 after four consecutive validation cycle in which the diagnostic runs without a fault.
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- The DTC(s) can be cleared by using the scan tool.

Step 1-8:

Step 9-14:

Troubleshooting