Circuit Description
The heated oxygen sensor (HO2S) is used to detect the oxygen content in the exhaust. The powertrain control module (PCM ) supplies the sensor with a signal circuit and with a ground circuit. The PCM supplies a bias voltage between the circuits. The sensor varies the voltage based on the oxygen content in the exhaust. When the exhaust stream is lean, indicating more oxygen, the sensor produces a low voltage signal. When the exhaust stream is rich, indicating less oxygen, the sensor produces a high voltage signal.
The PCM monitors the HO2S activity in order to determine a time ratio for the lean-to-rich switches, and for the rich-to-lean switches. The PCM counts the number of lean-to-rich and rich-to-lean switches for 100 seconds. The PCM records the time required to complete all transitions. With this information, the PCM determines an average transition time for the lean-to-rich switches and for the rich-to-lean switches.
| • | DTC P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0135, P0151, P0152, P0155, P0201-P0208, P0300, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416, P1441 are not set. |
| • | The engine speed is between 1200-2800 RPM. |
| • | The mass air flow (MAF) is between 15-35 g/s. |
| • | The throttle position (TP) angle is more than 3 percent. |
| • | The exhaust gas recirculation (EGR) flow test is not active. |
| • | The secondary air injection (AIR) system tests are not active. |
| • | The catalyst test is not active. |
| • | The system voltage is between 9-18 volts. |
| • | The engine coolant temperature is more than 75°C (167°F). |
| • | The transmission is not in park, reverse, or neutral. |
| • | The closed loop fuel control is enabled. |
| • | The above conditions are met for 3 seconds. |
Conditions for Setting the DTC
| • | The ratio of average transition times is not between 0.50 and 3.9. |
| • | The O2 voltage is between 325-625 mV. |
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
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
Notice: Do not solder heated oxygen sensor wires. Soldering the wires will result in the loss of the air reference to the sensor. Refer to Engine Electrical for proper wire and connection repair techniques.
Notice: Use the connector test adapter kit J 35616-A for any test that
requires probing the following items:
• The PCM harness connectors • The electrical center fuse/relay cavities • The component terminals • The component harness connector
If the condition is intermittent, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step checks if other possible causes of this diagnostic trouble code (DTC) have already been diagnosed.
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Diagnose other DTCs first because other DTCs may be the cause of this DTC setting.
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With the engine running warm and at fast idle, and with the coolant at least 85°C (185°F), the oxygen sensor voltage should rapidly swing above 625 mV and below 325 mV.
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This step checks if the oxygen sensor voltage is swinging between rich and lean very slowly, or not at all.
-
This step checks for causes of oxygen sensor failure. If the sensor is replaced without finding the cause of contamination, premature failure of the new sensor may result.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||
1 | Did you perform the Diagnostic System Check- Engine Controls? | -- | Go to Step 2 | |||||||
Were you sent here from another DTC? | -- | Go to Step 4 | Go to Step 3 | |||||||
Are any other DTCs set? | -- | Go to Step 4 | ||||||||
Does the HO2S voltage rapidly swing above and below the range specified? | 325-625 mV | Go to Step 5 | Go to Step 6 | |||||||
5 | With engine running at 2000 RPM, observe the scan tool display Loop Status. Does the display indicate Closed? | -- | Go to Diagnostic Aids | Go to Step 9 | ||||||
Does the HO2S voltage remain between the specified values more than the voltage swings outside this range? | 325-625 mV | Go to Step 9 | Go to Step 7 | |||||||
7 |
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8 | ||||||
8 |
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9 | ||||||
|
Important: Before you replace the oxygen sensor, you must find and correct the cause of the contamination. Check for the following conditions:
Replace HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 . Did you complete the replacement? | -- | Go to Step 10 | -- | |||||||
10 |
Does the DTC run and pass? | -- | Go to Step 11 | Go to Step 2 | ||||||
11 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||
