P0133

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The PCM continuously monitors the Heated Oxygen Sensor (HO2S) activity. During the monitoring period the PCM counts the number of times that the a rich to lean and lean to rich response is indicated and adds the amount of time it took 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 300mV to greater than 600mV. A rich to lean transition is indicated when the HO2S voltage changes from more than 600mV to less than 300mV. An HO2S that responds too slowly is likely to be faulty and should be replaced.

Conditions for Running the DTC

^ Vehicle speed above 32 km/h (20 mph) for 20 seconds in closed loop.

^ Barometric pressure greater than 75 kPa.

^ Fuel tank level greater than 25%.

^ Intake air temperature is between -10°C (14°F) and 50°C (122°F).


Conditions for Setting the DTC

^ Response rate average greater than 1 second. Switch cycle average greater than 5 seconds.

Action Taken When the DTC Sets

^ The Malfunction indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer.


Conditions for Clearing the MIL/DTC

^ The MIL will turn OFF after three consecutively passing cycles without a fault present.

^ A History DTC will clear after 40 consecutive warm-up cycles without a fault.

^ DTCs can be cleared by using a scan tool or by disconnecting the PCM battery feed.


Diagnostic Aids

Check for any of the following conditions:

^ If any DTCs other than Fuel Trim (P0171, P0172), Misfire (P0300 to P0303), EGR (P0400) and HO2S 1 (P0131 to P0134) are set, diagnosis those DTCs first.

^ A poor connection at the PCM. Inspect the harness connectors for backed out terminal, improper mating, broken locks, improperly formed or damaged terminals, and a poor terminal to wire connection.

^ A damaged wiring harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the HO2S 1 display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the HO2S 1 display will indicate the location of the fault.

If a DTC P0133 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.

If any wiring repairs need to be made, Refer to Repair Procedures in Electrical Diagrams.


Test Description

The numbers below refer to the step numbers in the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. Determines if the fault is present.

5. To ensure the HO2S 1 does not become contaminated, Check for any of the following conditions in this step.