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 difference between the rich-to-lean average transition time and the lean-to-rich transition time is more than a specified value, DTC P1134 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1134 HO2S Transition Time Ratio 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 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 Sensor parameter is between 6-40 percent. |
| • | The EVAP Purge Solenoid command 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 Air Flow Calculated parameter is more than 15 g/s. |
| • | DTC P1134 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 difference between the HO2S 1 rich-to-lean average transition time and the lean-to-rich average transition time is more than a calibrated value. |
| • | DTC P1134 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: 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 | ||||||||
|
Important: If DTC P0135 is set, diagnose that DTC first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information.
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 , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. 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 , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. 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 , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. 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 , Connector Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. 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 powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. 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 PCM. Refer to Control Module References in Computer/Integrating Systems 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? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK | ||||||||
