Circuit Description
The powertrain control module (PCM) monitors the heated oxygen sensor (HO2S) activity for 100 seconds. During this test period, the PCM counts the number of times that the HO2S signal voltage crosses the rich to lean and the lean to rich thresholds. A lean to rich switch is determined when the HO2S voltage changes from less than 300 mV to more 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. If the PCM determines that the HO2S did not switch enough times, DTC P1133 will set.
Conditions for Running the DTC
| • | No TP sensor, EVAP system, misfire, IAT sensor, MAP sensor, Fuel trim, injector circuit, EGR Pintle Position, MAF sensor, ECT sensor, CKP sensor, or H02S Sensor 1 heater circuit DTCs are set. |
| • | The mass air flow is between 10 g/s and 30 g/s. |
| • | The ECT is greater than 50°C (122°F). |
| • | The engine run time is more than 60 seconds. |
| • | The engine speed is between 1000 RPM and 3000 RPM. |
| • | The engine is running in closed loop. |
Conditions for Setting the DTC
| • | The above conditions are present for a 100-second monitoring period. |
| • | The PCM monitors fewer than 40 rich to lean and 40 lean to rich switches for HO2S 1. |
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/Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has 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 a scan tool. |
Diagnostic Aids
A malfunction in the HO2S heater ignition feed or ground circuit may cause the DTC to set. Inspect the HO2S heater circuitry for intermittent malfunctions or for poor connections. If the connections and the wiring are OK and the DTC continues to set, replace the HO2S 1.
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Loose terminal connection |
| - | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| - | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| • | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
| • | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
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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If the low circuit is shorted to ground, the HO2S voltage will be less than 400 mV when the signal circuit is jumped to ground.
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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.
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This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read-only memory (EEPROM). When you replace the PCM, you must program the new PCM.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
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Important: If any other DTCs set except the HO2S DTCs, refer to the other DTCs first before proceeding with this table.
Does the voltage vary outside the specified values? | 400-500 mV | |||||||||
3 | Operate vehicle within the Failure Records conditions. Does the scan tool indicate that this DTC failed this ignition? | -- | Go to Diagnostic Aids | |||||||
4 | Inspect and test for the following conditions:
Did you find and correct the condition? | -- | ||||||||
Is the HO2S voltage more than the specified value? | 400 mV | |||||||||
Is the voltage near the specified value? | 4.5V | |||||||||
Use a DMM that is connected to a good ground in order to measure the voltage on the HO2S low circuit on the PCM side. Is the voltage near the specified value? | 5V | |||||||||
8 | Test the low circuit for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||
9 | Test the signal circuit for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||
10 | Test the low circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||
11 | Test for poor connections at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||
12 |
Important: Determine the cause of contamination before replacing the sensor. Inspect and test for the following conditions:
Replace the affected HO2S sensor. Refer to Heated Oxygen Sensor Replacement . Did you complete the repair? | -- | -- | |||||||
13 | Test for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||
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Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the repair? | -- | -- | ||||||||
15 |
Does the DTC reset? | -- | ||||||||
16 | Use the scan tool in order to check for DTCs. Does the scan tool indicate any DTCs that you have not diagnosed? | -- | System OK |
