Circuit Description
The oxygen sensor (O2S) is a sensor designed to create a voltage relative to the oxygen content in the engine exhaust stream. The powertrain control module (PCM) supplies the O2S 1 with signal and return circuits. The oxygen content of the exhaust indicates when the engine is operating lean or rich. When the O2S detects that the engine is operating rich, the signal voltage is high and decreases the signal voltage as the engine runs leaner. This oscillation above and below the bias voltage, sometimes referred to as activity or switching, can be monitored with the O2S signal voltage.
The O2S needs to be at a high temperature in order to produce a voltage. Once the O2S has reached operating temperature, the control module monitors the O2S bias, or reference, voltage as well as the O2S signal voltage for Closed Loop fuel control. During normal Closed Loop fuel control operation, the PCM will add fuel, (enriched the mixture, when the O2S detects a lean exhaust content and subtract fuel, lean-out the mixture, when the O2S detects a rich exhaust condition.
This diagnostic trouble code (DTC) determines if the O2S is functioning properly by checking for an adequate number of O2S voltage transitions above and below the bias range of 300-600 mV within a given time frame. This DTC sets when the PCM fails to detect a minimum number of voltage transitions above and below the bias range during the test period time frame.
Conditions For Running The DTC
| • | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0169, P0171, P0172, P0178, P0179, P0201-P0204, P0300, P0301-P0304, P0336, P0440, P0446, P0446, P0452, P0453, P0506, P0507, P0601, P0602, or P1441 are not set. |
| • | The engine coolant temperature (ECT) is more than 70°C (158°F). |
| • | The engine run time more than 200 seconds. |
| • | The throttle position (TP) is between 9-18 percent. |
| • | The engine speed is between 1,600-2,450 RPM. |
| • | The fuel level is more than 10 percent . |
| • | The evaporative emission (EVAP) pulse width modulation (PWM) is more than 35.6 percent . |
| • | The engine is operating in Closed Loop. |
| • | The purge learned memory is more than approximately 0.78. |
| • | The fuel ethanol composition is less than 15 percent. |
| • | The manifold absolute pressure (MAP) is greater than 25 kPa. |
Conditions For Setting The DTC
The average O2S 1 response times are more than 1,119 mS for rich-to-lean sweeps, or 760 mS for lean-to-rich sweeps, or sum of the rich-to-lean and lean-to-- rich is greater than 1,235 mS.
The average O2S 1 L/R sweep is more than 971 mS for automatic transmission, or 1,111 mS for manual transmission.
Or
The average R/L added to the average L/R sweep is more than 971 mS for automatic transmission, or 1,111 mS for manual transmission.
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 System Inspection 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. |
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
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.
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This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||
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 | Operate vehicle within Failure Records conditions. Does the scan tool indicate this DTC failed 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 | ||||||
Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | |||||||
13 |
Does the DTC run and pass? | -- | Go to Step 14 | Go to Step 2 | ||||||
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||
