DTC P0132 HO2S Circuit High Voltage Sensor 1. Buick GL7 (Export) 2000

For 1990-2009 cars

### Circuit Description

The powertrain control module (PCM) supplies a bias voltage of about 450 mV between the heated oxygen sensor (HO2S) signal and low circuits. When measured with a 10 megaohm DMM, 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, CKP, misfire, fuel injector circuit, EVAP, or EGR DTCs are present.

• | The system voltage is more than 9.0 volts.

• | The Closed Loop commanded air/fuel ratio is between 14.4 and 14.9.

• | The throttle angle is between 5 and 40 percent.

### Conditions for Setting the DTC

• | The HO2S 1 signal voltage remains more than 975 mV for more than 16 seconds during normal Closed Loop operation

| OR:

• | The 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 the following items:

• | The 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 the Fuel Injector Balance Test. Refer to Fuel Injector Balance Test .

• | Inspect the EVAP canister for fuel saturation. If the canister is full of fuel, check the canister control and the hoses.

• | Disconnect the MAF sensor and see if the 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 checking the 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.

• | A shorted 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 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 .

• | An 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, check the HO2S signal and low circuit wiring and associated terminal connections. If the wiring and the connections are OK, replace the HO2S. Refer to Heated Oxygen Sensor Replacement .

### Test Description

The numbers below refer to step numbers on the diagnostic table.

1. This DTC failing during Deceleration Fuel mode operation, with the vehicle speed more than 40 km/h (25 mph) and the TP angle 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 determine how often the condition that caused the DTC to be set occurs.

2. This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read-only memory (EEPROM). If the PCM is replaced, the new PCM must be programmed.

#### HO2S 1 High

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check

2

1. Operate the vehicle within the Conditions for Setting the DTC.
2. With a scan tool, observe the HO2S voltage parameter.

Does the HO2S voltage remain more than the specified value?

600 mV

Go to Step 5

Go to Step 3

3 | Operate the vehicle in the Decel Fuel mode while observing the HO2S voltage parameter on the scan tool. Does the HO2S voltage remain more than the specified value? | 110 mV | Go to Step 5 | Go to Step 4
4 | Operate the vehicle within the Failure Records conditions. Does the scan tool indicate this DTC failed this ignition? | -- | Go to Step 5 | Go to Diagnostic Aids
5 | Disconnect the HO2S. Does the scan tool indicate the HO2S voltage is more than the specified value? | 500 mV | Go to Step 6 | Go to Step 8
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? | -- | Go to Step 9 | Go to Step 7
7 | Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the repair? | -- | Go to Step 9 | --
8 | Replace the HO2S. Refer to Heated Oxygen Sensor Replacement . Did you complete the repair? | -- | Go to Step 9 | --

9

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Failure Records conditions.

Does the DTC reset?

--

Go to Step 2

System OK