DTC P0133. Buick LeSabre 2001

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2001 🢒 LeSabre 🢒 Body and Accessories 🢒 Body Control System 🢒 DTC P0133

Circuit Description

The powertrain control module (PCM) continuously monitors the heated oxygen sensor (HO2S) activity for 100 seconds. During the monitoring period, the PCM counts the number of times that a rich-to-lean response and a lean-to-rich response are indicated, and adds the time used to complete all transitions. With this information, an average time for each transition can be determined. If the average response time is too slow, a DTC P0133 will be set. A lean-to-rich transition is indicated when the HO2S voltage changes from less than 300 mV to more than 600 mV. A rich-to-lean transition is indicated when the HO2S voltage changes from more than 600 mV to less than 300 mV. An HO2S that responds too slowly is likely to be malfunctioning and should be replaced.

Conditions for Running the DTC

•	DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0300, P0410, P0440, P0442, P0443, P0446, P0449, or P1441 are not set.

•	The engine has been running in Closed Loop fuel control for at least 60 seconds.

•	The engine speed is between 1,000-3,000 RPM.

•	The engine coolant temperature is more than 50°C (122°F).

•	The mass air flow is between 10-30 g/s.

Conditions for Setting the DTC

The HO2S 1 lean-to-rich average transition response time during the sample period was longer than 140 milliseconds, or the rich-to-lean average transition response time during the sample period was longer than 107 milliseconds.

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.

•	Clear the MIL and the DTC with a scan tool.

Test Description

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

When the system is operating correctly, the HO2S voltage should toggle above and below the specified values.

If the H02S high or low signal circuit is shorted to ground, the HO2S voltage will be less than 400 mV when the signal circuit is jumped to ground.

The specified value is what is measured on a correctly-operating system.

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Important: If any DTCs other than HO2S are set, perform those diagnostics first. Refer to Diagnostic Trouble Code (DTC) List .

Turn ON ignition and run engine at a normal operating temperature.
Operate engine above 1,200 RPM for 2 minutes.
Use a scan tool in order to observe the HO2S voltage parameter.

Does scan tool indicate HO2S voltage varying outside the specified values?

400-500 mV

Go to Step 3

Go to Step 4

Operate vehicle within the Failure Records conditions.

Does the scan tool indicate this DTC failed this ignition?

Go to Step 4

Go to Intermittent Conditions

Inspect and test for the following conditions:

•	An exhaust leak-- Refer to Exhaust Leakage in Engine Exhaust.

•	An incorrectly-installed H02S

•	Damaged wiring--Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 5

Turn ON the ignition.
Disconnect the HO2S.
Jumper the H02S high signal circuit on the PCM side to a good ground.
With a scan tool, observe HO2S voltage parameter.

Does the scan tool indicate HO2S voltage more than the specified value?

400 mV

Go to Step 6

Go to Step 10

Remove the jumper wire.
Measure the voltage on the HO2S high signal circuit on the PCM side, using a DMM that is connected to a good ground.

Does the voltage measure near the specified value?

4.5 V

Go to Step 7

Go to Step 9

Measure the voltage on the HO2S low signal circuit on the PCM side, using a DMM that is connected to a good ground.

Does the voltage measure near the specified value?

5 V

Go to Step 11

Go to Step 8

Test the H02S low signal circuit for an open or for for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 13

Test the signal H02S high signal circuit for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 13

Test the H02S low signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 14

Inspect for poor connections at the harness connector of the H02S sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Repair any conditions as necessary.

Did you find and correct the condition?

Go to Step 15

Go to Step 12

Notice: Contamination of the oxygen sensor can result from the use of an inappropriate RTV sealant (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove the HO2S and visually inspect the portion of the sensor exposed to the exhaust stream in order to check for contamination. If contaminated, the portion of the sensor exposed to the exhaust stream will have a white powdery coating. Silicon contamination causes a high but false HO2S signal voltage (rich exhaust indication). The control module will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Eliminate the source of contamination before replacing the oxygen sensor.

Important: Determine the cause of contamination before replacing the sensor.

Inspect and test for the following conditions:

•	Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Engine oil or coolant consumption--Refer to Oil Consumption Diagnosis in Engine Mechanical.

•	Use of an improper RTV sealant

Replace the affected HO2S sensor. Refer to Heated Oxygen Sensor 1 Replacement , or Heated Oxygen Sensor 2 Replacement .

Did you complete the replacement?

Go to Step 15

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 14

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 15

Use the scan tool in order to clear the DTCs.
Turn OFF the ignition for 30 seconds.
Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC run and pass?

Go to Step 16

Go to Step 2

With a scan tool observe the stored information in Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK