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 Running the DTC
| • | DTCs P0102, P0103, P0112, P0113, P0117, P0118, P0125, P0335, P0336, P0351-P0358, P1120, P1220, P1221, P1258 not set. |
| • | This DTC only runs once an ignition cycle. |
| • | System operating in Closed Loop |
| • | Engine operating longer than 120 seconds. |
| • | Engine speed greater than 1000 RPM but less than 2300 RPM. |
| • | Ignition voltage greater than 9.0 volts. |
| • | Engine coolant temperature greater than 65°C (149°F). |
| • | EVAP duty cycle greater than 0%. |
| • | MAF between 15 g/s and 35 g/s. |
Conditions for Setting the DTC
The PCM determines that within 100 seconds the HO2S lean to rich switches are less than 30 and rich to lean switches are less then 30.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Use a scan tool in order to clear the MIL and the DTC. |
Diagnostic Aids
Important: Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM\TAC modules.
| • | Inspect the HO2S signal circuit for being shorted to a PCM ground. The HO2S signal circuit shorted to a PCM ground will not cause a HO2S low DTC to set, but will set a switching DTC. |
| • | 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 Body and Accessories/Wiring Systems. |
| • | Using the 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 you observed. This will isolate when the DTC failed. |
For an intermittent, refer to Symptoms .
Test Description
The numbers below refer to the step numbers 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.
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DTCs P1133 and P1153 setting at the same time is a good indication that a fuel contamination condition 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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This step checks whether a good ground circuit is available.
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This step 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 the fuel. If the sensors appear contaminated by silicone and 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 | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||
|
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 the scan tool also indicate P1153 test failed? | -- | |||||||||||
Did you isolate an exhaust leak? | -- | |||||||||||
5 | Visually/physically inspect the following items:
Did you find a condition in any of the above areas? | -- | ||||||||||
Is the HO2S voltage within the specified range? | 350-550 mV | |||||||||||
7 |
Is the HO2S voltage below the specified value? | 200 mV | ||||||||||
|
Important: Before replacing a sensor, determine and correct the cause of the contamination.
Check for the following conditions:
Replace the affected Heated Oxygen sensor. Refer to Heated Oxygen Sensor Replacement . Is the action complete? | -- | -- | ||||||||||
9 | Repair the condition as necessary. Is the action complete? | -- | -- | |||||||||
10 | Repair the open Bank 1 HO2S 1 low signal circuit or grounded Bank 1 HO2S 1 high signal circuit. Is the action complete? | -- | -- | |||||||||
11 | Repair the open Bank 1 HO2S 1 high signal circuit or faulty PCM connections. Is the action complete? | -- | -- | |||||||||
12 | Replace the 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 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
