P0040
DTC P0040: HO2S Signals Swapped Bank 1 and 2 Sensor 1Wiring 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.
Conditions for Setting the DTC
- No oxygen sensor, ignition coil, misfire faults exist. The ECM detects the HO2S signal voltages are heading in the opposite direction of what was expected.
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 three 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
- For an intermittent fault condition, refer to Intermittents. The O2 sensor must be tightened correctly. A loose O2 sensor will trigger these DTCs. Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic procedure for shorted terminals or poor wiring connection before replacing any component. Intermittents
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DTC Troubleshooting