DTC P0133 HO2S Slow Response Sensor 1. Buick LeSabre 2000

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2000 🢒 LeSabre 🢒 DTC 🢒 DTC P0133 HO2S Slow Response Sensor 1

Engine Controls Components
HO2S 1, HO2S 2
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

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 and lean to rich response is indicated and adds the amount of 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

•	No TP sensor, EVAP system, misfire, IAT sensor, MAP sensor, fuel trim, fuel injector circuit, EGR pintle position, ECT sensor, HO2S heater circuit sensor 1, CKP, or MAF sensor DTCs present

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

•	Engine speed is between 1000 RPM and 3000 RPM.

•	ECT more than 50°C (122°F).

•	Mass Air Flow between 10 g/s and 30 g/s.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

•	The PCM will illuminate the 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 and Fail Records data.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has been 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 the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids

•	Inspect for the following conditions:

-	Poor connection at PCM

-	Backed out terminals

-	Improper mating

-	Broken locks

-	Improperly formed or damaged terminals

-	Poor terminal to wire connection--Use a corresponding mating terminal to check for proper terminal tension.

-	Damaged harness--If the harness appears to be OK, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the malfunction. Refer to Wiring Repairs .

•	If DTC P0133 cannot be duplicated, Reviewing the Fail 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.

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 low 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.

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.

DTC P0133

Step

Action

Value(s)

Yes

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

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

Engine at operating temperature.
Operate engine above 1200 RPM for two 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 Fail Records conditions.

Does the scan tool indicate this DTC failed this ignition?

Go to Step 4

Go to Diagnostic Aids

Inspect and test for the following:

•	Exhaust leak. Refer to Exhaust Leakage - Not OBD II in Engine Exhaust.

•	The HO2S is installed correctly.

•	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 signal circuit (PCM side) to a good ground.
Use a scan tool in order to 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 signal circuit (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 circuit (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 low circuit for an open or 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 circuit for an open or 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 low 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

Test for poor connections at the HO2S. 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 12

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

Inspect and test for the following:

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

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

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.