Circuit Description
The powertrain control module (PCM) supplies a voltage of about 447 mV between the heated oxygen sensor (HO2S 1) high signal and the low signal circuit. The HO2S 1 varies the voltage within a range of about 1000 mV if the exhaust is rich, down through about 100 mV if the exhaust is lean.
The sensor is like an open circuit and produces no voltage when below 315°C (600°F).
Do not attempt to repair the HO2S. Replace the entire HO2S 1 assembly 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, P0201, P0202, P0203, P0204, P0205, P0206, P0300, P0336, P0440, P0446, P0452, P0453, P0507, P0601, P0602, P0604, P0606, P1120, P1220, P1221, P1271, P1275, P1280, P1484, P1512, P1514, P1515, P1516, P1621, P1635, P1639, P1680, or P1681 are not set. |
| • | The fuel level sensor is more than 10 percent. |
| • | The ignition 1 signal is more than 10 volts. |
| • | The engine coolant temperature (ECT) is more than 80°C (176°F). |
| • | The throttle position (TP) indicated angle is between 15-50 percent for 20 seconds. |
| • | The accelerator pedal position (APP) indicated angle is more than 1.2 percent. |
| • | The manifold absolute pressure (MAP) sensor is more than 25 kPa. |
| • | The engine run time is more than 30 seconds. |
| • | The mass air flow (MAF) is more than 7 g/s. |
Conditions For Setting The DTC
The HO2S 1 voltage is between 399-499 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 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 Open Loop operation. |
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. |
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 HO2S 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: 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 scan tool indicate HO2S voltage varying outside the specified values? | 400-500 mV | Go to Step 3 | Go to Step 4 | |||||||
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | |||||||
4 | Inspect and test for the following conditions:
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 HO2S voltage at or near the specified value? | 0 mV | Go to Step 9 | Go to Step 7 | |||||||
7 | Test the HO2S low signal circuit for an open, high resistance, or short to voltage. 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 HO2S high signal circuit for an open, high resistance, or short to voltage. 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 HO2S. 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 conditions:
Notice: Contamination of the oxygen sensor can result from the use of an inappropriate RTV sealant (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove the HO2S and visually inspect the portion of the sensor exposed to the exhaust stream in order to check for contamination. If contaminated, the portion of the sensor exposed to the exhaust stream will have a white powdery coating. Silicon contamination causes a high but false HO2S signal voltage (rich exhaust indication). The control module will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Eliminate the source of contamination before replacing the oxygen sensor.
Replace the affected HO2S sensor. Refer to Heated Oxygen Sensor 1 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 |
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 | |||||||
