P0133

Heated Oxygen Sensor (HO2S) Slow Response Sensor 1:

Heated Oxygen Sensor (HO2S) Circuit Sensor 1:

Circuit Description

The PCM continuously monitors the Heated Oxygen Sensor (HO2S) activity. 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 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 3OOmV to greater than 6OOmV. A rich to lean transition is indicated when the HO2S voltage changes from more than 6OOmV to less than 3OOmV. 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.
^ DTC(s) can be cleared by using a scan tool or by disconnecting the PCM battery feed.


Diagnostic Aids

Check The Following Conditions:

^ If DTC's other than Fuel Trim (P0171, P0172), Misfire (P0300 to P0304), Exhaust Gas Recirculation (EGR) (P0400) and HO2S 1 (P0131 to P0134) are set, diagnose those DTC's first.
^ Poor connection at PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
^ Damaged 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 DTC P0134 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 Diagrams.

Test Description

Number(s) below refer to the step number(s) on 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 the following conditions in this step.