Circuit Description
Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started, the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperatures and Closed Loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream. Low HO2S voltage indicates a lean exhaust stream.
This diagnostic will only run once per ignition cycle. The PCM monitors the rich-to-lean and lean-to-rich transition time. A transition is defined as the HO2S voltage changes from above 650 mV to below 350 mV or from below 350 mV to above 650 mV. If the PCM detects that the transition time is too long, DTC P0133 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0133 HO2S Slow Response Sensor 1
Conditions for Running the DTC
| • | DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0128, P0201-P0204, P0300, P0315, P0336, P0442, P0446, P0452, P0453, P0455, P0496, P0506, P0507, P0601, P0602, P1621 are not set. |
| • | The ECT Sensor parameter is more than 70°C (158°F). |
| • | The Ignition 1 Signal parameter is more than 11 volts. |
| • | The Fuel Level Sensor parameter is more than 10 percent. |
| • | The Engine Run Time parameter is more than 200 seconds. |
| • | The Engine Speed parameter is between 1,000-3,500 RPM. |
| • | The MAP Sensor parameter is between 10-104 kPa. |
| • | The change in throttle position is less than 800 percent per second. |
| • | The Air Flow Calculated parameter is more than 15 g/s. |
| • | The Loop Status parameter is closed. |
| • | The TP Sensor parameter is between 6-40 percent. |
| • | The EVAP Purge Solenoid command is more than 36 percent. |
| • | The intrusive catalyst monitor tests are inactive. |
| • | DTC P0133 runs once per drive cycle when the above conditions are met for 0.75 second. |
Conditions for Setting the DTC
| • | The PCM detects that the HO2S 1 rich-to-lean or lean-to-rich average response time is more than a calibrated value. |
| • | DTC P0133 sets within 60 seconds when the above condition is met. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connect End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||||
2 |
Important: If any other DTCs are set, refer to the other DTCs before proceeding with this table. Are any other DTCs set? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | Go to Step 3 | ||||||||
3 |
Does the scan tool indicate that the heated oxygen sensor (HO2S) 1 voltage is varying above and below the specified values? | 350-650 mV | Go to Step 4 | Go to Step 5 | ||||||||
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions | ||||||||
5 |
Important: Before replacing the HO2S, locate and correct any source of contamination.
Did you complete the replacement? | -- | Go to Step 6 | -- | ||||||||
6 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 7 | ||||||||
7 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK | ||||||||
