P0134
DTC P0134 O2S Circuit Insufficient Activity Sensor 1
Circuit Description
The Powertrain Control Module (PCM) supplies a voltage of about 0.45 volt to oxygen sensor 1 (O2S 1). The O2S 1 voltage varies from about 1 volt if the exhaust is rich, to about 0.10 volt if the exhaust is lean.
The O2S 1 circuit is open and produces no voltage when the O2S 1 temperature is below 315° C (600° F). An open O2S 1 circuit or a cold sensor causes an open loop operation.
Conditions for Running the DTC
- There are no active manifold absolute pressure (MAP) DTCs.
- There are no active intake air temperature (IAT) DTCs.
- There are no active engine coolant temperature (ECT) DTCs.
- There are no active throttle position (TP) DTCs.
- There are no active fuel trim DTCs.
- There are no active injector control DTCs.
- There are no active misfire DTCs.
- There are no active crankshaft position (CKP) DTCs.
- There are no active evaporative emissions (EVAP) DTCs.
- There are no active idle air control (IAC) DTCs.
- The air flow is more than 3 grams per second.
- The engine coolant temperature (ECT) is more than 70° C (155° F).
- The throttle position (TP) angle is between 4 - 56 percent.
- The engine has been running for more than 30 seconds.
Conditions for Setting the DTC
O2S 1 voltage is between 399 - 499 mV for 125 seconds.
Action Taken When the DTC Sets
- The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive ignition cycles.
- The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is recorded in the scan tool's Freeze Frame and Failure Records.
Conditions for Clearing the MIL/DTC
- The MIL will turn off after 3 consecutive ignition cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 consecutive warm-up cycles without a fault.
- The DTCs can be cleared using the scan tool Clear Information function.
Diagnostic Aids
- When the oxygen sensor pigtail wiring, connector or terminal are damaged, the entire oxygen sensor assembly must be replaced. Do not attempt to repair the wiring, the connector or the terminals. In order for the sensor to function properly, the O2S must have a clean air reference. This clean air reference is obtained by way of the oxygen sensor wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degrade the performance of the sensor.
- The normal scan tool voltage varies between 150 - 850 mV (0.15 - 0.85 volt) when in a closed loop. DTC P0134 sets in approximately 88 seconds when the voltage remains between 0.407 - 0.509 volt. The system will go into an open loop in about 30 seconds.
Step 1:
Steps 2 - 4:
Steps 5 - 7:
Steps 8 - 10:
Steps 11 - 13:
Steps 14 - 15:
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
2. This step checks for proper sensor activity. When in Closed Loop fuel control the HO2S voltage should rapidly swing above and below the bias voltage.
4. This step checks the PCM and the HIGH and LOW circuits between the PCM and the HO2S connector for proper operation.
7. This step checks for proper HO2S heater circuit operation up to the HO2S connector.
8. This step checks for proper circuit resistance between the HO2S LOW circuit and PCM ground.
13. This step checks for proper circuit resistance between the HO2S LOW circuit and PCM ground with a COLD sensor. A loose HO2S or poor tread to exhaust electrical contact will cause higher resistance when the HO2S is cold. Although 500 ohms is allowed, typical resistance should be less than 50 ohms.