P0152

CIRCUIT DESCRIPTION
The Heated Oxygen Sensor (HO2S) is a sensor used to detect oxygen-content in the exhaust. The Powertrain Control Module (PCM) supplies the sensor with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The sensor varies the voltage based on the oxygen content in the exhaust. When the exhaust stream is lean (more oxygen), the sensor produces a low voltage signal. When the exhaust stream is rich (less oxygen), the sensor produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, the PCM adjusts the injector pulse width. If the HO2S bank 2 sensor 1 remains too high for a calibrated period of time, DTC P0152 will set.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416, or P1441 are not set.
^ The throttle position angle is between 3-25 percent.
^ The system voltage is between 9-18 volts.
^ The closed loop fuel control is enabled.
^ The air/fuel ratio is between 14.40 and 14.90.
^ The conditions above met for 3 seconds.
^ The AIR diagnostic test is not active.
^ The Exhaust Gas Recirculation (EGR) flow diagnostic test is not active.
^ The catalyst diagnostic is not active.

CONDITIONS FOR SETTING THE DTC
^ The HO2S bank 2 sensor 1 signal voltage remains above 900 mV deceleration fuel control.

OR

^ The HO2S bank 2 sensor 1 signal voltage remains above 200 mV (0.2 V) during Deceleration Fuel Cut Off (DFCO) control.

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.
^ Use a scan tool in order to clear the MIL and the DTC.

DIAGNOSTIC AIDS

NOTE:
^ Refer to Heated Oxygen Sensor (HO2S) Wire Repair Notice in Service Precautions.
^ Refer to Connector Test Adapter kit J 35616-A Notice in Service Precautions.

Check the following items:
^ The HO2S wire routing-The sensor wiring may be routed incorrectly and contacting the exhaust system.
^ The fuel pressure-Fuel pressure that is too high will cause a rich condition. The PCM will compensate for some increase. However, if the fuel pressure is too high, DTC P0132 may set.
^ The fuel injector-If the fuel injectors deliver improper fuel volume at the specified pressure, DTC P0132 may set. Refer to Fuel Injector Balance Test with Special Tool and Fuel Injector Balance Test with Tech 2. Component Tests and General Diagnostics Component Tests and General Diagnostics
^ The EVAP canister-Check the EVAP canister and hoses for fuel saturation.
^ Silicon contamination-Silicon contamination of the HO2S can also cause a high HO2S signal voltage. This condition is indicated by a powdery white deposit on the portion of the HO2S exposed to the exhaust stream.

Review the front and rear long term fuel trim values on the scan tool Failure Records. If both banks were rich, check for a condition that would cause a rich engine operation. If only the rear bank was rich, the rich condition is isolated to that bank, such as an intermittent open HO2S ground circuit or an intermittent short to voltage on the signal circuit.

If the condition is intermittent, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-8:

The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies whether the HO2S voltage is switching from below 300 mV to above 600 mV, or remaining above 600 mV.
4. This step verifies the bias voltage from the PCM and the condition of the circuit wiring. With the sensor disconnected, the scan tool should display a bias voltage near 450 mV.