P0133

Refer to Underhood HO2S in Engine Controls Schematics.

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

CIRCUIT DESCRIPTION
The 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 taken 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 faulty and should be replaced.

CONDITIONS FOR RUNNING THE DTC
^ Active TP, MAP, MAF, IAT, ECT, or AIR, misfire, fuel injector circuit, or EVAP DTCs are not present
^ Engine has been running in Closed Loop for at least 1 minute
^ MAF between 10 grams per second and 30 grams per second.
^ System voltage between 9.0 and 18.0 volts.
^ Engine speed is between 1000 RPM and 3000 RPM
^ ECT is more than 50°C (122°F).
^ Vehicle not in Park or Neutral
^ AIR pump commanded OFF.

CONDITIONS FOR SETTING THE DTC
^ HO2S 1 lean to rich average transition response time was longer than 94 milliseconds.
^ HO2S 1 rich to lean average transition response time was longer than 105 milliseconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM will illuminate the Malfunction Indicator Lamp (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 Failure Records data.
^ If the misfire is determined to be catalyst damaging, the PCM will flash the MIL

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn OFF the MIL 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 a scan tool.

DIAGNOSTIC AIDS
Inspect for the following conditions:

IMPORTANT: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

^ Poor terminal connection-Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension.
^ Damaged harness-Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault.
^ PCM and engine grounds for clean and secure connections

If the DTC is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table:
2. When the system is operating correctly the HO2S voltage should toggle above and below the specified values.
5. 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.
6. The specified value is what is measured on a correctly operating system.
7. The specified value is what is measured on a correctly operating system.
14. 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.