Circuit Description
The PCM monitors the Heated Oxygen Sensor (HO2S) activity for 100 seconds. During this monitor period the PCM counts the number of times that the HO2S switches form rich to lean and lean to rich. When the PCM determines that the HO2S did not switch enough times, a DTC P1133 will 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 Setting the DTC
| • | DTCs P0100, P0102, P0103, P0107, P0108, P0117, P0118, P0123, P0200, P0372, P1371 not set. |
| • | System operating in Closed Loop |
| • | Engine speed greater than 1000 RPM but less than 1700 RPM. |
| • | MAF between 12 gm/s and 28 gm/s. |
| • | The PCM determines that within 100 seconds the HO2S lean to rich switches are less than 40 and rich to lean switches are less then 30. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails. |
| • | The PCM will record operating conditions at the time the diagnostic fails. The first time the diagnostic fails, this information will be stored in Failure Records. If the diagnostic reports a failure on the second consecutive drive trip, the operating conditions at the time of failure will be written to Freeze Frame and the Failure record will be updated. |
Conditions for Clearing the MIL/DTC
| • | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | A last test failed (Current DTC) will clear when the diagnostic runs and does not fail. |
| • | PCM battery voltage is interrupted. |
| • | Using a scan tool. |
Diagnostic Aids
| • | A malfunction in the HO2S heater circuits will cause a DTC P1133 to set. Check HO2S heater circuits for intermittent opens/connections. |
| • | An oxygen supply inside the HO2S is necessary for proper operation. This supply of oxygen is provided through the HO2S wires. All HO2S wires and connections should be inspected for breaks or contamination. Refer to Repair Procedures in Electrical Diagnosis (8A Cell 5). |
| • | Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that were noted. This will isolate when the DTC failed. |
For intermittents, refer to Symptoms .
Test Description
Number(s) below refer to step numbers on the diagnostic table.
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Determines if the fault is present. This test may take 5 minutes for the diagnostic to run.
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When DTCs P1133 and P1153 are set at the same time, is good indication that a fuel contamination problem is present.
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An exhaust leak 6 to 12 inches away from the HO2S can cause a DTC to set.
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Checks whether a good ground circuit is available.
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Checks the integrity of the signal circuit to the PCM.
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Certain RTV silicone gasket materials give off vapors that can contaminate the HO2S. There is also a possibility of silicone contamination caused by silicone in fuel. If it appears that the sensors are contaminated by silicon and all silicone sealant is a non silicone base, advise customer to try a different fuel company. A fuel filler restrictor missing, indicates leaded fuel may have been used.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||
|
Important: If any DTCs are set (Except P1153), refer to those DTCs before proceeding with this diagnostic table.
Does the scan tool indicate DTC P1133 test failed? | -- | Go to Diagnostic Aids | ||||||||||
Did scan tool also indicate P1153 test failed? | -- | |||||||||||
Was an exhaust leak isolated? | -- | |||||||||||
5 | Visually/physically inspect the following items:
Was a problem found in any of the above areas? | -- | ||||||||||
Does the scan tool indicate voltage within specified values? | 375 mV to 525 mV | |||||||||||
7 |
Does the scan tool indicate voltage below specified value? | 200 mV | ||||||||||
|
Important: Before replacing a sensor, the cause of the contamination must be determined
and corrected. Check for the following conditions:
Replace the affected Heated Oxygen Sensor. Refer to Heated Oxygen Sensor Replacement . Is the action complete? | -- | -- | ||||||||||
9 | Repair condition as necessary. Is the action complete? | -- | -- | |||||||||
10 | Repair open Bank 1 HO2S 1 low signal circuit or grounded Bank 1 HO2S 1 high signal circuit. Is the action complete? | -- | -- | |||||||||
11 | Repair open Bank 1 HO2S 1 high signal circuit or faulty PCM connections. Is the action complete? | -- | -- | |||||||||
12 | Replace Bank 1 HO2S 1. Refer to Heated Oxygen Sensor Replacement . Is the action complete? | -- | -- | |||||||||
13 |
Does the scan tool indicate that this test ran and passed? | -- | ||||||||||
14 | Using the scan tool, select Capture Info, Review Info. Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
