Circuit Description
The Powertrain Control Module (PCM) supplies a bias voltage of approximately 450 mV between the heated oxygen sensor (HO2S) signal and the low circuits. When measured with a 10 megaohm digital voltmeter (DVM), this may display as low as 320 mV. The oxygen sensor varies the voltage from approximately 1000 mV when the exhaust is rich, to approximately 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 time, DTC P0132 will be set.
Conditions for Running the DTC
| • | There are no active TP, MAP, MAF, ECT, IAT, fuel injector circuit, EVAP or AIR diagnostic trouble codes (DTCs) present. |
| • | The system voltage is between 9.0 and 18.0 volts. |
| • | The closed loop commanded air-to-fuel ratio is between 14.5 and 14.8. |
| • | The throttle angle between 5 percent and 40 percent . |
| • | The AIR pump is commanded OFF. |
Conditions for Setting the DTC
| • | HO2S 1 signal voltage remains more than 977 mV for longer than 50 seconds during normal closed loop operation. |
| OR |
| • | HO2S 1 signal voltage remains more than 200 mV for more 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:
| • | Fuel pressure--The system will go rich if pressure is too high. The PCM can compensate for some increase. However, if the fuel pressure is too high, refer to Fuel System Pressure Test . |
| • | Perform the injector balance test-- Refer to Fuel Injector Balance Test . |
| • | Inspect the EVAP canister for fuel saturation. If the canister is full of fuel, inspect the canister 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 . |
| • | Test for a leaking fuel pressure regulator diaphragm by checking the vacuum line to the 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. |
| • | A shorted heated oxygen sensor (HO2S)-- If the HO2S is internally shorted, the HO2S voltage displayed on the scan tool will be more than 1.0 volt. Disconnect the affected HO2S and jumper the HO2S low circuit to ground with the key ON , and the engine OFF. If the displayed HO2S voltage changes from more than 1000 mV to approximately 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 that is exposed to the exhaust stream. If you notice contamination, replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement . |
| • | An open HO2S signal or low circuit or faulty HO2S--A faulty connection or an 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 of 300 mV to 600 mV, check the HO2S signal and low circuit wiring and the 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.
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This DTC failing during deceleration fuel mode operation, when the vehicle speed is more than 25 mph and the TP angle is less than 3 percent, may indicate a condition described in Diagnostic Aids. If this DTC test passes while the Failure Records conditions are being duplicated, an intermittent condition is indicated. Review the Failure Records vehicle mileage since the diagnostic test last failed. This may help to determine how often the condition that caused the DTC to be set occurs.
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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 the HO2S voltage parameters. If all of the 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, with the vehicle speed more than 25 mph and the TP angle less than 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? | 110 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 that the HO2S voltage is 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 replacement? | -- | -- | ||
8 | Replace the HO2S. Refer to Heated Oxygen Sensor Replacement . Did you complete the replacement? | -- | -- | |
9 |
Does the DTC reset? | -- | System OK |
