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 engine control module (ECM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started, the ECM 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 ECM monitors the number of rich-to-lean and lean-to-rich transitions. If the ECM detects that the number of transitions were less than a specified value, DTC P1133 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1133 HO2S Insufficient Switching Sensor 1
Conditions for Running the DTC
| • | DTCs P0068, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0122, P0123, P0125, P0128, P0201, P0202, P0203, P0204, P0220, P0300, P0315, P0336, P0442, P0446, P0452, P0453, P0455, P0496, P0506, P0507, P0601, P0602, P0604, P0606, P0641, P0651, P1516, P1621, P1680, P1681, P2101, P2120, P2125, P2135, P2138, P2176 are not set. |
| • | The ECT Sensor parameter is more than 70°C (158°F). |
| • | The Engine Speed parameter is between 1,000-3,500 RPM. |
| • | The Ignition 1 Signal parameter is more than 11 volts. |
| • | The Engine Run Time parameter is more than 200 seconds. |
| • | The Loop Status parameter is closed. |
| • | The TP Angle parameter is between 6-60 percent. |
| • | The EVAP Purge Solenoid DC parameter is more than 35 percent. |
| • | The Fuel Level Sensor parameter is more than 10 percent. |
| • | The MAP Sensor parameter is between 10-104 kPa. |
| • | The above conditions are met for 0.75 second. |
| • | DTC P1133 runs once per drive cycle when the above conditions are met. |
Conditions for Setting the DTC
| • | The ECM detects that the HO2S 1 rich-to-lean counts 2, or the lean-to-rich counts is less than a calibrated value. |
| • | DTC P1133 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. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||
|
Important: If DTC P0135 is set, diagnose that DTC first. Refer to Diagnostic System Check - Vehicle .
Is the HO2S 1 parameter varying above and below the specified range? | 300-600 mV | Go to Step 3 | Go to Step 4 | |||||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions | ||||||||
4 |
Is the HO2S 1 parameter less than the specified value? | 100 mV | Go to Step 6 | Go to Step 5 | ||||||||
5 |
Is the HO2S 1 parameter less than the specified value? | 100 mV | Go to Step 8 | Go to Step 7 | ||||||||
6 | Test the HO2S 1 high signal circuit for a short to the HO2S 1 low signal circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 | ||||||||
7 | Test the HO2S 1 high signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 | ||||||||
8 |
Is the HO2S 1 parameter less than the specified value? | 100 mV | Go to Step 10 | Go to Step 9 | ||||||||
9 | Test the HO2S 1 low signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 | ||||||||
10 | Test for shorted terminals and for poor connections at the HO2S 1. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12 | ||||||||
11 | Test for shorted terminals and for poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13 | ||||||||
12 |
Notice: Refer to Silicon Contamination of Heated Oxygen Sensors Notice in the Preface section. Important: The HO2S 1 may be damaged due to contamination.
Did you complete the replacement? | -- | Go to Step 14 | -- | ||||||||
13 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 14 | -- | ||||||||
14 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 15 | ||||||||
15 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||
