GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2008 🢒 LaCrosse 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P0133

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0133: HO2S Slow Response Sensor 1

Circuit Description

The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell, and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow, or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low, and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio.

Conditions for Running the DTCs
    • Before the ECM can report DTC P0133 failed, DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, P0338, and P2237 must run and pass.
    • DTCs P0030, P0031, P0032, P0053, P0130, P0131, P0132, P0135, P0442, P0443, P0446, P0455, P0458, P0459 P167A, P2096, P2097, P2231, P2243, P2251, P2297, and P2626 are not set.
    • The HO2S is at operating temperature.
    • The calculated exhaust temperature at the HO2S 1 is less than 570°C (1,058°F).
    • The fuel trim is enabled.
    • The HO2S is between 0.94-1.06 lambda.
    • The engine speed is between 1,360-2,520 RPM.
    • The volumetric efficiency is between 17-50 percent.
    • The change in volumetric efficiency is less than 3 percent.
    • The evaporative emission (EVAP) purge is not active, or the ECM determines the EVAP hydrocarbon (HC) concentration is less than a predetermined threshold.
    • The short term fuel trim is enabled and within the minimum/maximum correction.
    • DTC P0133 runs continuously once the above conditions are met for 2 seconds, then 60 test samples covering approximately 10 minutes.

Conditions for Setting the DTCs
    • The ECM has determined that the dynamic response of the affected HO2S is 40 percent less than a predetermined value.
    • The above condition is exists for greater than 4 seconds, or for a cumulative of 50 seconds.

Action Taken when the DTCs Set

DTC  P0133 is a Type B DTC.

Conditions for Clearing the MIL/DTCs

DTC  P0133 is a Type B DTC.

Diagnostic Aids

The following table illustrates the ECM connector locations:

ECM Connector Location

X2

X1

Front of Vehicle

    • The front wide band sensor does not toggle or switch like a switching HO2S. The front HO2S signal will be relatively stable for an idling engine.
    • The following table illustrates the typical voltages for the HO2S circuits:

HO2S Circuit

Voltage

    • Ignition ON, Engine OFF
    • HO2S Disconnected

Heater Control

4.6-5.0 V

Heater Supply Voltage

B+

High Signal

2.6-3.1 V

Low Signal

2.2-2.7 V

Pump Current

Less than 0.5 V

Input Pump Current

Less than 0.5 V

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Ignition ON, observe the scan tool DTC information. Verify no other DTCs are set.
    2. ⇒If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  2. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

Circuit/System Testing
  1. Verify that none of the following conditions exist:
    2. • Inspect the HO2S 1 for being secure
    • Lean or rich fuel injectors--Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2
    • Water intrusion in the HO2S harness connector
    • HO2S wiring harness damage
    • Incorrect RTV sealant
    • Incorrect fuel system pressure--Refer to Fuel System Diagnosis
    • Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis
    • Fuel saturation of the evaporative emission (EVAP) canister
    • Exhaust leaks near the HO2S--Refer to Exhaust Leakage
    • Engine vacuum leaks
    • Engine oil consumption--Refer to Oil Consumption Diagnosis
    • Engine coolant consumption--Refer to Loss of Coolant
         ⇒If you find any of the above conditions, repair as necessary.
  2. If all conditions test normal, replace the HO2S 1.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Heated Oxygen Sensor 1 Replacement
    •  Control Module References for engine control module replacement, setup, and programming