P0050

DTC P0050: HO2S Heater Control Circuit Bank 2 Sensor 1

Wiring Diagram:

Circuit Description
Heated oxygen sensors 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 Engine Control Module (ECM) operates in an Open Loop mode, ignoring the HO2S signal voltage when calculating the air fuel ratio. The ECM supplies the HO2S with a reference voltage of about 0.45 V. The HO2S generates a voltage within a range of 0 - 1 V that fluctuates above and below bias voltage once in Closed Loop. 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 then provide an accurate voltage signal. The ECM controls the HO2S heater low control circuit with a low side driver. The HO2S heater diagnostic monitors the current draw through the HO2S low side driver when the engine is running. If the ECM detects that the HO2S heater low control circuit current exceeds a calibrated amount, this DTC will set.

Conditions for Setting the DTC
- Ignition ON with the engine running.
- Battery voltage is higher than 10.46 V.
- Heater driver PWM duty cycle is less than 0.39% or higher than 99.69%.

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.

Step 1 - 11:

DTC Troubleshooting