Circuit Description
The powertrain control module (PCM) monitors the heated oxygen sensor (HO2S) activity. During the monitoring period, the PCM counts the number of times that the HO2S responds from rich to lean and from lean to rich, and adds the amount of time needed to complete all transitions. With this information, an average time for all transitions can be determined. The PCM then divides the rich-to-lean average by the lean-to-rich average in order to obtain a ratio. A DTC P1134 or a P1154 sets if the HO2S ratio is not within range. This diagnostic runs once per ignition cycle.
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0300, P0410, P0440, P0442, P0446, P0452, P0453, P1258, P1415, P1416, or P1441 are not set. |
| • | The loop status is closed. |
| • | The engine run time is more than 160 seconds. |
| • | The engine speed is between 1,000-2,300 RPM. |
| • | The ignition 1 signal is between 9-18 volts. |
| • | The engine coolant temperature (ECT) is more than 50°C (122°F). |
| • | The evaporative emissions (EVAP) purge solenoid is more than 0 percent. |
| • | The mass air flow (MAF) is between 20-50 g/s. |
| • | The throttle position (TP) is more than 5 percent. |
| • | The fuel tank level remaining is more than 10 percent. |
| • | The above conditions are met for 60 seconds. |
Conditions for Setting the DTC
The PCM determines that the HO2S transition time ratio is more than or less than the calibrated range.
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. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step determines if the condition is present. This test may take 5 minutes for the diagnostic to run.
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When DTCs P1134 and P1154 are set at the same time, a fuel contamination condition is likely.
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An exhaust leak 6-12 inches away from the HO2S can cause a DTC to set.
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This step tests whether a good ground circuit is available.
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This step tests the integrity of the HO2S high signal circuit to the PCM.
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This step tests the integrity of the HO2S high signal circuit to the PCM.
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Certain RTV silicone gasket materials release vapors that can contaminate the HO2S. Silicone in the fuel can also cause silicone contamination. If the sensors appear silicon-contaminated, and if all the silicone sealant is a non-silicone base, advise the customer to try a different fuel company. A missing fuel filler restrictor indicates the customer may have used leaded fuel.
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: If any DTCs are set except DTC P1134 or P1154, refer to those DTCs before proceeding with this diagnostic table.
Did DTC P1134 or P1154 fail this ignition? | -- | Go to Step 3 | Go to Intermittent Conditions | |||||||||
Did both DTC P1134 and P1154 fail this ignition? | -- | Go to Step 8 | Go to Step 4 | |||||||||
Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 5 | |||||||||
Inspect for the following conditions:
Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 6 | |||||||||
Does the scan tool indicate a voltage within the specified range? | 350-550 mV | Go to Step 7 | Go to Step 10 | |||||||||
Does the scan tool indicate a voltage below the specified value? | 200 mV | Go to Step 13 | Go to Step 9 | |||||||||
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Important: Determine and correct the cause of the contamination before replacing
a sensor. Inspect for the following conditions:
Replace the affected Heated Oxygen sensor. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 and/or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 . Did you complete the replacement? | -- | Go to Step 14 | -- | |||||||||
9 |
Does the DMM indicate a voltage near the specified value? | 5 V | Go to Step 12 | Go to Step 11 | ||||||||
10 |
Notice: A short to voltage on the heated oxygen sensor (HO2S) high signal circuit may damage the HO2S. Repair the HO2S high signal circuit for a short to ground or short to voltage. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 14 | -- | ||||||||
11 | Repair the open in the HO2S low signal circuit or repair the poor PCM connections. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 14 | -- | ||||||||
12 | Repair the HO2S high signal circuit for an open or repair the poor PCM connections. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 14 | -- | ||||||||
13 | Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 and/or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 . Did you complete the replacement? | -- | Go to Step 14 | -- | ||||||||
14 |
Does the DTC run and pass? | -- | Go to Step 15 | Go to Step 2 | ||||||||
15 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||
