Circuit Description
The PCM monitors the Heated Oxygen Sensor (HO2S) activity. During the monitor 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 it took 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 to obtain a ratio. A DTC P1134 sets if the HO2S ratio is not within range.
Conditions for Setting the DTC
| • | DTCs P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0200, P0335, P0336, P0351-P0358, P1258 not set. |
| • | The fuel system is operating in Closed Loop. |
| • | The engine run time is greater than 120 seconds. |
| • | The engine speed is greater than 1200 RPM but less than 3000 RPM. |
| • | The ignition voltage is greater than 9.0 volts. |
| • | The engine coolant temperature is greater than 65°C (149°F). |
| • | The MAF is between 23 g/s and 50 g/s. |
| • | The EVAP purge duty cycle is greater than 0%. |
Conditions for Setting the DTC
The PCM determines that the HO2S transition time ratio is not at the expected value.
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 connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
| • | 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. |
| • | 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 Heated Oxygen Sensor Wiring Repairs in Wiring Systems. |
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. For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616 . Using this kit prevents damage to the harness connector terminals. Refer to Using Connector Test Adapters in Wiring Systems.
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When DTCs P1134 and P1154 are set at the same time, it is a good indication that a fuel contamination condition is present.
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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 the HO2S for being tight and the connectors and circuits are OK.
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This step tests the integrity of the HO2S Low signal circuit to the PCM.
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This step tests the integrity of the signal circuits 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 to be 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 P1154), refer to those DTCs before proceeding with this diagnostic table.
Did DTC P1134 fail this ignition? | -- | Go to Diagnostic Aids | ||||||||||
Did DTC P1154 also fail this ignition? | -- | |||||||||||
Did you isolate an exhaust leak? | -- | |||||||||||
Visually/physically inspect the following items:
Did you find and correct the condition? | -- | |||||||||||
Does the scan tool indicate a voltage within the specified range? | 350-550 mV | |||||||||||
Does the scan tool indicate a voltage below 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 - Bank 1 and/or Heated Oxygen Sensor Replacement - Bank 2 . Is the action complete? | -- | -- | ||||||||||
9 |
Does the DMM indicate a voltage near the specified value? | 5V | ||||||||||
10 | Repair the high signal circuit for a short to ground or a short to voltage. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||||
11 | Repair the open HO2S low circuit or repair the faulty PCM connections. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||||
12 | Repair the HO2S high signal circuit for an open or repair the faulty PCM connections. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||||
13 | Replace the HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 . Is the action complete? | -- | -- | |||||||||
14 |
Does the scan tool indicate that this test ran and passed? | -- | ||||||||||
15 | 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 |
