Circuit Description
The PCM monitors the Heated Oxygen Sensor (HO2S) activity. The PCM counts the number of times that the HO2S signal voltage crosses the rich to lean and lean to rich thresholds during a 100 second test period. If the PCM determines that the HO2S did not switch enough times, DTC P1133 will be set. A lean to rich switch is determined when the HO2S voltage changes from less than 300 mV to greater than 600 mV. A rich to lean switch is determined when the HO2S voltage changes from more than 600 mV to less than 300 mV.
Conditions for Running the DTC
| • | No Fuel Injector, MAF, TP, EVAP, IAT, MAP, Fuel Trim, EGR or ECT DTCs are set. |
| • | DTC P0135 is not set. |
Conditions for Setting the DTC
| • | The PCM monitors fewer than 40 lean to rich and rich to lean switches for Bank 1 HO2S 1. |
| • | The HO2S voltage remains between 300 and 600 millivolts. |
| • | The conditions are present for a 2 minute after closed loop enable. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed. |
| • | The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool. |
Diagnostic Aids
A malfunction in the HO2S heater ignition feed or ground circuit may cause a DTC P1133 to set. Check HO2S heater circuitry for intermittent faults or poor connections. If connections and wiring are OK and DTC P1133 continues to set, replace the Bank 1 HO2S 1. Review the Fail 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.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
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This step determines if the fault is present. This test may take 5 minutes for the diagnostic to run.
-
A condition that affects other heated oxygen sensors indicates probable contamination. To avoid damaging replacement sensors, correct the condition which caused the contamination before replacing the affected sensors.
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A exhaust leak 6 to 12 inches away from the HO2S can cause this DTC to set.
-
This step tests for conditions which may cause the heated oxygen sensor to appear faulty. Correct any of the described conditions if present.
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This step tests for a short to ground in the signal circuit to the PCM. If the signal circuit is shorted to ground the scan tool will display less than 200mV.
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This step tests for a short to ground in the low circuit to the PCM. If the low circuit is shorted to ground the scan tool will display less than 200mV.
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This step tests the integrity of both the signal and low circuits to the PCM. If the circuits are functioning properly the scan tool will display less than 200mV.
-
To avoid damaging replacement sensors, correct the condition which caused the contamination before replacing the affected sensors.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||
|
Important: If any DTCs are set (except HO2S DTCs), refer to those DTCs before proceeding with this table.
Does scan tool indicate this DTC failed this ignition? | -- | Go to Diagnostic Aids | ||||||||||
Does the scan tool also indicate other HO2S DTCs set? | -- | |||||||||||
Inspect the exhaust system for a leak. Refer to Exhaust System Inspection in Engine Exhaust. Did you find and correct the condition? | -- | |||||||||||
Visually/physically inspect the following items:
Did you find and correct the condition? | -- | |||||||||||
Does the scan tool indicate HO2S voltage within the specified range? | 350-550 mV | |||||||||||
Does the scan tool indicate HO2S voltage within the specified range? | 350-550 mV | |||||||||||
Does the scan tool indicate HO2S voltage less than the specified value? | 200 mV | |||||||||||
|
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 . Did you complete the repair? | -- | -- | ||||||||||
10 | Repair the condition as necessary. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |||||||||
11 | Repair the short to ground in the HO2S Low circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |||||||||
12 | Repair the short to ground in the HO2S Signal circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | -- | |||||||||
13 | Test for the following conditions:
Refer to Wiring Repairs or Intermittents and Poor Connections Diagnosis and Connector Repairs . Did you complete the repair? | -- | -- | |||||||||
14 | Inspect for poor connections at the HO2S. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs . Did you find and correct the condition? | -- | ||||||||||
15 | Replace the HO2S. Refer to Heated Oxygen Sensor Replacement . Did you complete the replacement? | -- | -- | |||||||||
16 |
Does the DTC reset? | -- | ||||||||||
17 | Does the scan tool indicate any DTCs set that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
