P0152
DTC P0152 - HO2S Circuit High Voltage Bank 2 Sensor 1
Circuit Description
The powertrain control module (PCM) supplies a bias voltage of about 450 mV between the heated oxygen sensor (HO2S) signal high and signal low circuits. When measured with a 10 megaohm digital voltmeter, this may display as low as 320 mV. The oxygen sensor varies the voltage within a range of about 1000 mV when the exhaust is rich, down through about 10 mV when exhaust is lean. The PCM constantly monitors the HO2S signal during closed loop operation and compensates for a rich or lean condition by decreasing or increasing the injector pulse width as necessary. If the Bank 2 HO2S 1 voltage remains excessively high for an extended period of time, DTC P0152 will be set.
Conditions for Setting the DTC
- No related DTCs.
- The engine is operating in closed loop.
- The engine coolant temperature is above 60 °C (140 °F).
- Closed loop commanded air/fuel ratio between 14.5 and 14.8.
- Throttle angle between 3% and 19%.
- Bank 2 HO2S 1 signal voltage remains above 952 mV during normal closed loop operation for a total of 77 seconds over a 90-second period.
OR
- Bank 2 HO2S 1 signal voltage remains above 500 mV during deceleration fuel cutoff mode operation for up to 3 seconds.
Action Taken When the DTC Sets
- The PCM will illuminate the malfunction indicator lamp (MIL) the first time the fault is detected.
- The PCM will store conditions which were present when the DTC was set as Freeze-Frame and in the Failure Records data.
- Open loop fuel control will be in effect.
Conditions for Clearing the MIL/DTC
- The PCM will turn the MIL OFF on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
- A history DTC P0152 will clear after 40 consecutive warm-up cycles have occurred without a fault.
- DTC P0152 can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.
Diagnostic Aids
Check for the following conditions:
- Fuel pressure - The system will go rich if pressure is too high. The PCM can compensate for some increase. However, if fuel pressure is too high, a DTC P0152 may be set. Refer to Fuel System Diagnosis.
- Rich injector(s) - Perform Injector Balance Test.
- Leaking injector - Refer to Fuel System Diagnosis.
- Evaporative emissions (EVAP) system - Check the canister for fuel saturation. If the canister is full of fuel, check EVAP control system components and hoses. Refer to Evaporative Emission (EVAP) Control System.
- MAF sensor - The system can go rich if the MAF sensor signal indicates an engine airflow measurement that is not correct. Disconnect the MAF sensor to see if rich condition is corrected. If so, replace MAF sensor.
- Check for leaking fuel pressure regulator diaphragm by checking vacuum line to regulator for the presence of fuel. There should be no fuel in the vacuum line.
- TP sensor - An intermittent TP sensor output will cause the system to go rich, due to a false indication of the engine accelerating.
- Shorted Heated Oxygen Sensor (H02S) - If the H02S is internally shorted, the H02S voltage displayed on the scan tool will be over 1 volt. Try disconnecting the affected HO2S with the key ON, engine OFF. If the displayed H02S voltage changes from over 1000 mV to around 450 mV, replace the H02S. Silicon contamination of the H02S can cause a high H02S voltage to be indicated. This condition is indicated by powdery white deposit on the portion of the H02S exposed to the exhaust stream. If contamination is noticed, replace the affected H02S.
- Open H02S Signal Circuit of Faulty H02S - A poor connection or open in the H02S signal circuit can cause the DTC to set during deceleration fuel mode. An H02S which is faulty and not allowing a full voltage switch between the rich and lean thresholds can also cause the condition. Operate the vehicle while monitoring the HO2S voltage with a scan tool. If the H02S is limited within a range between 300 mV to 600 mV, check the H02S signal circuit wiring and associated terminal connections.
- If none of the above conditions are present, replace the affected H02S.
Steps 1 - 8:
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart.
3. DTC P0152 failing during deceleration fuel cutoff mode operation may indicate a condition described in the Diagnostic Aids above. If the DTC P0152 test passes while the Failure Records conditions are being duplicated, an intermittent condition is indicated.
Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.