Circuit Description
The Powertrain Control Module (PCM) supplies a voltage of about 0.45 volt between the Oxygen Sensor (O2S 1) signal and the ground circuit. The Oxygen Sensor (O2S 1) varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volt if the exhaust is lean.
The sensor is like an open circuit and produces no voltage when below 315°C (600°F). An open sensor circuit or a cold sensor causes an Open Loop operation.
Replace the entire oxygen sensor (O2S 1) assembly. Do not attempt to repair the oxygen sensor if the following conditions exist:
| • | Damaged wiring |
| • | Damaged electrical connector |
| • | Damaged terminals |
Conditions For Running The DTC
| • | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0201, P0202, P0203, P0204, P0300, P0335, P0440, P0442, P0446, P0506, P0507, P0601, P0602, or P1441 not set. |
| • | Air flow is greater than 3 grams per second. |
| • | Engine Coolant Temperature (ECT) is greater than 70°C (158°F). |
| • | Engine is operating in Closed Loop. |
| • | Throttle Position (TP) angle is between 8 percent and 50 percent. |
| • | Engine has been in the above conditions for 20 seconds. |
Conditions For Setting The DTC
O2S 1 voltage is less than 44 mV for 125 seconds.
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the malfunction present. |
| • | The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers. |
| • | A history DTC stores. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm up cycles without a fault. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
| • | Fuel pressure -- System will be lean if pressure is too low. It may be necessary to monitor fuel pressure while driving the vehicle at various road speeds and/or loads to confirm. Refer to the Fuel System Diagnosis . |
| • | MAP sensor -- An output that causes the PCM to sense a lower than normal manifold pressure, or high vacuum, can cause the system to go lean. Disconnecting the MAP sensor will allow the PCM to substitute a fixed, or default, value for the MAP sensor. If the lean condition is gone when the MAP sensor is disconnected, refer to the Manifold Absolute Pressure Sensor Output Diagnosis for further diagnosis. |
| • | Fuel contamination -- Water, in even small amounts, near the in-tank fuel pump inlet, can be delivered to the injector. The water causes a lean exhaust and can set a DTC P0131. |
| • | Sensor harness -- The O2S 1 sensor pigtail may be mis-positioned and contacting the exhaust manifold. |
| • | Engine misfire -- A misfiring cylinder will result in unburned oxygen in the exhaust, which could cause a DTC P0131. Refer to the DTC P0300 Engine Misfire Detected and/or Symptoms . |
| • | Cracked Oxygen sensor (O2S 1) -- A cracked O2S 1 sensor or poor ground at the O2S 1 sensor could cause a DTC P0131. Refer to Symptoms . |
| • | Plugged fuel filter -- A plugged fuel filter can cause a lean condition and cause a DTC P0131 to set. |
| • | Plugged Oxygen Sensor (O2S 1) -- A plugged reference port on the Oxygen Sensor (O2S 1) will indicate a lower then normal voltage output from the O2S 1 sensor. |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
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This DTC failing during power enrichment operation, where the throttle position (TP) angle is more than 60%, may indicate a condition described in Diagnostic Aids. If this DTC test passes while the Fail Records conditions are being duplicated, an intermittent condition is indicated. Review the Fail Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.
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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 | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Does the voltage remain below the specified value? | 400 mV | ||
Operate vehicle within Fail Records conditions. Does the scan tool indicate this DTC failed this ignition? | -- | Go to Diagnostic Aids | ||
4 |
Does scan tool indicate O2 voltage less than the specified value? | 400 mV | ||
5 | Test the signal circuit for a short to ground or a short to the sensor ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
|
Important: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming Replace the PCM. Did you complete the repair? | -- | -- | ||
7 | Inspect the vehicle for any of the conditions in diagnostic Aids. If no problem is found, replace the O2 SENSOR. Refer to Oxygen Sensor Replacement . Did you complete the repair? | -- | -- | |
8 |
Does the DTC reset? | -- | System OK |
