Circuit Description
The powertrain control module (PCM) supplies a voltage of about 450 mV between the heated oxygen sensor (HO2S) high and low signal circuits. The oxygen sensor varies the voltage from about 1,000 mV when the exhaust is rich, through about 10 mV when the exhaust is lean.
The PCM monitors and stores the HO2S voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time in which the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period, and determines if the majority of the samples are out of the operating range.
The PCM monitors the HO2S voltage, and detects if the voltage goes out of the bias range. If the PCM does not detect that the voltage went out of the bias range, a diagnostic trouble code (DTC) sets.
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0300, P0351, P0401, P0404, P0405, P0440, P0442, P0446, P0452, P0453, P1258, P1404, P1441 are not set. |
| • | The engine run time is more than 409 seconds. |
| • | The loop status is closed. |
| • | The ignition 1 signal is between 9 volts and 18 volts. |
| • | The fuel tank level remaining is more than 10 percent. |
| • | The TP sensor changes more than 5 percent within 1 second, 6 times. |
Conditions for Setting the DTC
The HO2S signal voltage is between 400 mV and 475 mV for 145 seconds.
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: Before you service the PCM, remove any debris from the PCM connector surfaces. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
| • | An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Systems. |
| • | For an intermittent condition, refer to Symptoms - Engine Controls . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Before you perform this test, the engine must be at the normal operating temperature. For any test that requires probing the PCM or a probing component harness connector, use the J 35616 Connector Test Adapter Kit . Using this kit prevents damage to the harness connector terminals. Refer to Using Connector Test Adapters in Wiring Systems.
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Using the Freeze Frame/Failure Records may help to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records can help to determine how many miles have occurred since the DTC set. You can also use the Fail Counter and the Pass Counter in order to determine how many ignition cycles have occurred since the diagnostic reported a pass and/or a fail. In order to isolate when the DTC failed, operate the vehicle within the same freeze frame conditions that the PCM recorded. These conditions include the RPM, the vehicle load, the vehicle speed, and the temperature.
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If the scan tool indicates the HO2S voltage goes below 200 mV, the HO2S circuits and the PCM are OK.
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This step tests whether the low signal circuit from the PCM is OK. A voltage indicates that the PCM and the wiring are OK.
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Disconnecting the PCM allows using the DMM in order to test the circuit continuity. This helps to locate a circuit that is open or shorted.
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Disconnecting the PCM allows you to use the DMM in order to test the circuit continuity. This helps to locate a circuit that is open or shorted.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
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Important: Inspect the HO2S for being secure before proceeding with this DTC. A sensor that is loose could cause this DTC to set.
Does the scan tool indicate that the HO2S voltage varies outside the specified range? | 350-550 mV | Go to Step 3 | Go to Step 4 | |
Does the scan tool indicate that this diagnostic failed this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | |
Is the HO2S voltage below the specified value? | 200 mV | Go to Step 8 | Go to Step 5 | |
Does the DMM indicate near the specified value? | 5 V | Go to Step 6 | Go to Step 7 | |
Did you find and correct the HO2S high circuit condition? | -- | Go to Step 12 | Go to Step 10 | |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | |
8 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
9 | Replace the appropriate HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 . Did you complete the repair? | -- | Go to Step 12 | -- |
10 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
11 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Does the DTC run and pass? | -- | Go to Step 13 | Go to Step 2 |
13 | With a scan tool observe the Stored information, Capture info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
