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 O2S 1 varies the voltage within a range of about 1 volt if the exhaust is rich, 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.
Do not attempt to repair the oxygen sensor. Replace the entire O2S 1 assembly if the following conditions exist:
| • | Any damaged wiring |
| • | A damaged electrical connector |
| • | Any damaged terminals |
Conditions For Running The DTC
| • | The following DTCs are not set: P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0171, P0201, P0202, P0203, P0204, P0300, P0335, P0440, P0442, P0446, P0506, P0507, P0601, P0602, or P1441. |
| • | The air flow is more than 3 g/s. |
| • | The engine coolant temperature (ECT) is more than 70°C (158°F). |
| • | The engine is operating in Closed Loop. |
| • | The throttle position (TP) angle is between 5 percent and 50 percent. |
| • | The above conditions are met for 20 seconds. |
Conditions For Setting The DTC
The O2S 1 voltage is less than 52 mV for 125 seconds.
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) will illuminate after 2 consecutive ignition cycles in which the diagnostic runs with the fault active. |
| • | 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. |
| • | The vehicle will operate in an Open Loop mode. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn off after 3 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
| • | The system will be lean if the pressure is too low. It may be necessary to monitor the fuel pressure while driving the vehicle at various road speeds and various loads in order to confirm the condition. Refer to Fuel System Diagnosis . |
| • | A manifold absolute pressure (MAP) sensor output that causes the PCM to sense a lower than normal manifold pressure (high vacuum) can cause the system to go lean. Disconnecting the MAP sensor will allow the PCM to substitute a default value for the MAP sensor. If the lean condition is corrected when you disconnect the sensor, refer to Manifold Absolute Pressure Sensor Output Diagnosis for further diagnosis. |
| • | Water, even in small amounts, near the in-tank fuel pump inlet can travel to the fuel injector. The water causes a lean exhaust and can set DTC P0131. |
| • | Ensure that the O2S 1 pigtail is not contacting the exhaust manifold. |
| • | A misfiring cylinder will result in unburned oxygen in the exhaust, which could cause DTC P0131. Refer to DTC P0300 Engine Misfire Detected . |
| • | A cracked O2S 1 or a poor ground at the sensor could cause a DTC P0131. |
| • | PA plugged fuel filter can cause a lean condition and cause a DTC P0131 to set. |
| • | A plugged reference port on the O2S 1 will indicate a lower than normal voltage output from the O2S 1. |
An intermittent could be the result of the following conditions:
| • | A poor electrical connection |
| • | A rubbed-through wire insulation |
| • | A broken wire inside of the insulation |
Inspect for a poor electrical connection or a damaged harness. Inspect the harness electrical connectors for the following conditions:
| • | Any incorrect mating |
| • | Any broken locks |
| • | Any incorrectly formed electrical connectors |
| • | Any damaged terminals |
| • | A poor terminal-to-wire connection |
| • | A damaged harness |
Do not attempt to repair the oxygen sensor. Replace the entire O2S 1 assembly if the following conditions exist:
| • | Any damaged wiring |
| • | A damaged electrical connector |
| • | Any damaged terminals |
Test Description
The numbers below refer to step numbers on the diagnostic table:
-
This DTC failing during power enrichment operation may indicate a condition described in Diagnostic Aids. If this DTC test passes while the Failure Records conditions are being duplicated, an intermittent condition is indicated. Review the Failure 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.
-
The replacement PCM must be reprogrammed and the Crankshaft Position System Variation Learn procedure must be preformed.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |
2 |
Does the voltage remain less than the specified value? | 400 mV | Go to Step 4 | Go to Step 3 |
Operate vehicle within the Failure Records conditions. Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | |
4 |
Is the voltage less than the specified value? | 400 mV | Go to Step 5 | Go to Step 7 |
5 | Test the signal circuit for a short to ground or a short to the sensor ground circuit. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 6 |
|
Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the repair? | -- | Go to Step 8 | -- | |
7 | Inspect the vehicle for any of the conditions in Diagnostic Aids. If no problem is found, then replace the oxygen sensor. Refer to Oxygen Sensor Replacement . Did you complete the repair? | -- | Go to Step 8 | -- |
8 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
