Circuit Description
Oxygen sensors (O2S) are used for fuel control and post catalyst monitoring. Each O2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The O2S must reach operating temperature to provide an accurate voltage signal. A heating element in O2S 2 minimizes the time required for the sensor to reach operating temperature. The powertrain control module (PCM) supplies the O2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the O2S voltage signal. Once the O2S reaches operating temperature and Closed Loop is achieved, the O2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High O2S voltage indicates a rich exhaust stream. Low O2S 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 O2S voltage changes from above 600 mV to below 300 mV or from below 300 mV to above 600 mV. If the PCM detects that the transition time is too long, DTC P0133 will set.
Conditions For Running The DTC
| • | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0172, P0201-P0204, P0300, P0301-P0304, P0336, P0440, P0446, P0452, P0453, P0506, P0507, P0601, P0602, or P1441 are not set. |
| • | The ECT Sensor parameter is more than 70°C (158°F). |
| • | The Engine Run Time parameter is more than 200 seconds. |
| • | The TP Sensor parameter is between 10-22 percent. |
| • | The Engine Speed parameter is between 1,600-2,300 RPM. |
| • | The Fuel Level Sensor parameter is more than 10 percent . |
| • | The EVAP Purge Solenoid Command is more than 35 percent . |
| • | The Loop Status parameter is closed. |
| • | The MAP Sensor parameter is more than 10 kPa. |
Conditions For Setting The DTC
The PCM detects that the O2S 1 rich-to-lean or lean-to-rich average response time is more than a calibrated value.
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. |
Diagnostic Aids
Important: Never solder the O2S wires. For proper wire and connector repairs, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Check for the following conditions:
| • | An improperly installed air cleaner outlet duct |
| • | The air cleaner outlet duct for collapsed ducting, restrictions, or a missing or plugged air filter |
| • | Throttle body and intake manifold vacuum leaks |
| • | A damaged or blocked throttle body inlet |
| • | Exhaust system for corrosion, leaks, or loose or missing hardware--Refer to Exhaust Leakage in Engine Exhaust. |
| • | The O2S is installed securely and the pigtail harness is not contacting the exhaust manifold |
| • | O2S contamination |
| • | The vacuum hoses for splits, kinks and proper connections |
| • | Excessive water or other contaminants in the fuel |
| • | PCM sensor grounds that are clean, tight and properly positioned |
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 O2S voltage should toggle above and below the specified values.
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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.
Step | Action | Values | 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-Engine Controls? | -- | Go to Step 2 | |||||||
|
Important: If any other DTCs are set, except HO2S DTCs, refer to other DTCs first before proceeding with this table.
Does the scan tool indicate O2 voltage varying outside the specified values? | 400-500 mV | Go to Step 3 | Go to Step 4 | |||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||
4 | Inspect and test for the following:
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 5 | ||||||
Does the voltage measure near the specified value? | 450 mV | Go to Step 6 | Go to Step 8 | |||||||
Does the scan tool indicate O2S voltage at or near the specified value? | 0 mV | Go to Step 9 | Go to Step 7 | |||||||
7 | Test the low 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? | -- | Go to Step 13 | Go to Step 11 | ||||||
8 | Test the high 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? | -- | Go to Step 13 | Go to Step 11 | ||||||
9 | Test for poor connections at the O2S. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||||
10 |
Important: Determine the cause of contamination before replacing the sensor. Inspect and test for the following:
Replace the O2S. Refer to Oxygen Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
11 | Test for poor 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? | -- | Go to Step 13 | Go to Step 12 | ||||||
12 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 | ||||||
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||
