Circuit Description
The powertrain control module (PCM) continuously monitors the heated oxygen sensor (HO2S) activity for 120 seconds. 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 300 mV to greater 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
| • | None of the following active DTCs are present: |
| - | Throttle position (TP) sensor |
| - | Evaporative emissions (EVAP) system |
| - | Misfire |
| - | Intake air temperature (IAT) sensor |
| - | Manifold absolute pressure (MAP) sensor |
| - | Fuel trim |
| - | Fuel injector circuit |
| - | EGR pintle position |
| - | Engine coolant temperature (ECT) sensor |
| - | Crankshaft position (CKP) sensor |
| - | Mass air flow (MAF) sensor |
| • | The engine has been running in closed loop fuel control for at least 60 seconds. |
| • | The engine speed is between 1000 RPM and 3000 RPM. |
| • | The engine coolant temperature is more than 50°C (122°F). |
| • | The mass air flow is between 10 g/s and 30 g/s. |
Conditions for Setting the DTC
VIN K--HO2S 1 lean to rich average transition response time during the sample period was more than 140 milliseconds or rich to lean average transition response time during the sample period was more than 107 milliseconds.
VIN 1--HO2S 1 lean to rich average transition response time during the sample period was more than 130 milliseconds or rich to lean average transition response time during the sample period was more than 110 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/Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has 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
Check for the following conditions:
| • | Faulty connections at PCM--Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections. Use a corresponding mating terminal to test for proper terminal tension. |
| • | 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 display will indicate the location of the malfunction. 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.
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When the system is operating correctly the HO2S voltage should toggle to more than and less than the specified values.
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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.
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The specified value is what is measured on a correctly operating system.
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The specified value is what is measured on a correctly operating system.
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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.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||||||||||
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Important: If any other DTCs are set (except HO2S DTCs), refer to the other DTCs before proceeding with this table.
Is the HO2S voltage varying outside the specified range? | 400-500 mV | |||||||||||
3 | Operate the vehicle within the Failure Records conditions. Does the scan tool indicate this DTC failed this ignition? | -- | Go to Diagnostic Aids | |||||||||
4 | Inspect and test for the following:
Did you find and correct the condition? | -- | ||||||||||
Is the HO2S voltage more than the specified value? | 400 mV | |||||||||||
Does the voltage approximately equal the specified value? | 4.5 V | |||||||||||
Measure the voltage on the HO2S low circuit (PCM side) using the DMM connected to a good ground. Does the voltage approximately equal the specified value? | 5 V | |||||||||||
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? | -- | ||||||||||
9 | 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? | -- | ||||||||||
10 | 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? | -- | ||||||||||
11 | Test for faulty 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? | -- | ||||||||||
12 |
Important: Determine the cause of contamination before replacing the sensor. Inspect and test for the following:
Replace the affected HO2S sensor. Refer to Heated Oxygen Sensor Replacement . Did you complete the repair? | -- | -- | |||||||||
13 | Test for faulty connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||||
|
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the repair? | -- | -- | ||||||||||
15 |
Does the DTC reset? | -- | ||||||||||
16 | Use the scan tool in order to check for DTCs. Does the scan tool indicate any DTCs that you have not diagnosed? | -- | System OK |
