Circuit Description
The PCM continuously monitors the Heated Oxygen Sensor (HO2S) activity. The PCM counts the number of times that a rich to lean and a lean to rich response is indicated. Then, the PCM adds the amount of time it took to complete all transitions for a 100 second test period. 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 greater 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
| • | No Misfire, CKP, Fuel Injector, MAF, TP, EVAP, IAT, MAP, Fuel Trim, EGR or ECT DTCs are present. |
| • | The engine coolant temperature is above 50°C (122°F). |
| • | Engine speed is between 1000 RPM and 3000 RPM. |
| • | Mass Air Flow is between 13.0 g/s and 30 g/s. |
Conditions for Setting the DTC
Bank 1 H02S 1 lean to rich average transition response time was longer than 150 milliseconds. The rich to lean average transition response time was longer than 130 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. |
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 the scan tool. |
Diagnostic Aids
Check for the following conditions:
| • | Poor connection at the PCM - Inspect harness connectors for the following conditions: |
| - | Backed out terminals. |
| - | Improper mating. |
| - | Broken locks. |
| - | Improperly formed or damaged terminals. |
| - | Poor terminal to wire connection. |
| • | Damaged harness -- Inspect the wiring harness for damage. If the harness appears to be OK, observe the Bank 1 H02S 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 fault. |
If DTC P0133 cannot be duplicated, Review the Freeze Frame/Fail Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
-
This step verifies that the fault is currently present.
-
HO2S transition time, ratio mean volts and switching DTCs set for multiple sensors indicate probable contamination. Before replacing the sensors, isolate and correct the source of the contamination to avoid damaging the replacement sensors.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||
|
Important:: If any other DTCs are set (except HO2S DTCs), refer to them first.
Does the scan tool indicate this DTC failed this ignition? | -- | Go to Diagnostic Aids | ||||||||||
Did the scan tool also indicate any other HO2S DTCs failed this ignition? | -- | |||||||||||
4 | Inspect for an exhaust leak. Did you find and correct the condition? | -- | ||||||||||
5 | Visually/physically inspect the following items:
Did you find a problem? | -- | ||||||||||
6 |
Does the scan tool indicate HO2S voltage near the specified value? | 450 mV | ||||||||||
7 |
Does scan tool indicate HO2S voltage below specified value? | 300 mV | ||||||||||
8 |
Important:: Determine and correct the cause of the contamination before replacing sensors. Inspect for the following conditions:
Replace affected Heated Oxygen Sensors. Refer to Heated Oxygen Sensor Replacement . Did you complete the repair? | -- | -- | |||||||||
9 | Repair condition as necessary. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |||||||||
10 | Repair an open or high resistance in the HO2S low circuit or a short to ground in the HO2S signal circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |||||||||
11 | Repair an open in the HO2S signal circuit or faulty PCM connections. Refer to Wiring Repairs and Connector Repairs . Did you complete the repair? | -- | -- | |||||||||
12 | Replace the HO2S. Heated Oxygen Sensor Replacement . Did you complete the repair? | -- | -- | |||||||||
13 |
Does the DTC reset? | -- | System OK |
