Refer to Engine Controls Schematic
HO2S #1 and HO2S #2
.
Circuit Description
The PCM supplies a bias voltage of about 450 mV between the HO2S signal and 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 injector pulse width as necessary. If the HO2S 1 voltage remains excessively high for an extended period of time, DTC P0132 will be set.
Conditions for Running the DTC
| • | No active TP, MAP, MAF, ECT, IAT sensor, fuel injector circuit, EVAP or AIR DTCs present. |
| • | System voltage between 9.0 and 18.0 volts. |
| • | Closed loop commanded air/fuel ratio is between 13.0 and 16.5. |
| • | Throttle angle between 5 percent and 40 percent. |
| • | AIR is commanded OFF. |
Conditions for Setting the DTC
| • | HO2S 1 signal voltage remains above 977 mV for longer than 50 seconds during normal closed loop operation. |
| OR |
| • | HO2S 1 signal voltage remains above 200 mV for longer than 29 seconds during deceleration fuel mode operation. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
Inspect for the following items:
| • | 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. Refer to Fuel System Pressure Test . |
| • | Perform Injector Balance Test. Refer to Fuel Injector Balance Test . |
| • | Inspect the EVAP Canister for Fuel Saturation. If full of fuel, inspect canister control and hoses. |
| • | Disconnect the MAF sensor and see if rich condition is corrected. If so, replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . |
| • | Inspect for a leaking fuel pressure regulator diaphragm by viewing vacuum line to regulator for the presence of fuel. |
| • | 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 (HO2S). -- If the HO2S is internally shorted the HO2S voltage displayed on the scan tool will be over 1.0 volt. Disconnect the affected HO2S and jumper the HO2S low circuit to ground with the key ON , engine OFF. If the displayed HO2S voltage changes from over 1000 mV to around 450 mV, replace the HO2S. Silicon contamination of the HO2S can also cause a high HO2S voltage to be indicated. This condition is indicated by a powdery white deposit on the portion of the HO2S exposed to the exhaust stream. If contamination is noticed, replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement . |
| • | Open HO2S Signal or Low Circuit or Faulty HO2S -- A poor connection or open in the HO2S signal or low circuit can cause the DTC to set during deceleration fuel mode. An HO2S which is faulty and not allowing a full voltage swing between the rich and lean thresholds can also cause this condition. Operate the vehicle while monitoring the HO2S voltage with a scan tool. If the HO2S voltage is limited within a range between 300 mV to 600 mV, inspect the HO2S signal and low circuit wiring and associated terminal connections. If the wiring and connections are OK, replace the HO2S. Refer to Heated Oxygen Sensor Replacement . |
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Loose terminal connection |
| - | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| - | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| • | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
| • | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Test Description
The numbers below refer to step numbers on the diagnostic table:
-
This DTC failing during deceleration fuel mode operation (vehicle speed above 25 mph, TP angle below 3 percent) may indicate a condition described in Diagnostic Aids. If this DTC test passes while the Fail Records conditions are being duplicated, an intermittent condition is indicated. Review the Fail Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.
-
This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Important: During this step, observe all HO2S voltage parameters. If all parameters remain above the specified value refer to Diagnostic Aids.
Does the HO2S voltage remain above the specified value? | 977 mV or 200 mV during deceleration fuel mode | ||
Operate vehicle in decel fuel mode (vehicle speed above 25 mph, TP angle below 3 percent) while observing the HO2S voltage parameter on the scan tool. Does the HO2S voltage remain above the specified value while in decel fuel mode? | 200 mV | |||
4 | Operate the vehicle within the Failure Records conditions. Does the scan tool indicate this DTC failed this ignition? | -- | Go to Diagnostic Aids | |
5 | Disconnect the HO2S. Does scan tool indicate HO2S voltage more than the specified value? | 500 mV | ||
6 | Test for a short to voltage on the HO2S signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
|
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the repair? | -- | -- | ||
8 | Replace the HO2S. Refer to Heated Oxygen Sensor Replacement . Did you complete the repair? | -- | -- | |
9 |
Does the DTC reset? | -- | System OK |
