P0134

CIRCUIT DESCRIPTION

Engine Control Schematics: Heated Oxygen Sensors (HO2S):

The HO2S is a sensor used to detect oxygen-content in the exhaust. The PCM supplies the sensor with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The sensor varies the voltage based on the oxygen content in the exhaust. When the exhaust stream is lean (more oxygen), the sensor produces a low voltage signal. When the exhaust stream is rich (less oxygen), the sensor produces a high voltage signal.

The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, the PCM adjusts the injector pulse width. If HO2S bank 1 sensor 1 remains at or near the bias voltage for a calibrated period of time, DTC P0134 will set.

CONDITIONS FOR RUNNING THE DTC
^ No MAF, TP, EVAP, IAT, MAP, AIR (if equipped), ECT, or Injector DTCs set.
^ EGR flow diagnostic inactive.
^ AIR diagnostic test (if equipped) inactive.
^ Catalyst diagnostic test inactive.
^ System voltage between 9 and 18 volts.
^ Engine running for more than 200 seconds.
^ Change in TP angle more than 5 percent occurs at least 4 times.

CONDITIONS FOR SETTING THE DTC
HO2S bank 1 sensor 1 signal voltage remain within 400 and 500 mV for approximately 57 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test runs and fails.
^ The PCM stores the conditions present when the DTC set as Freeze Frame and Fail Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes.
^ The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using the scan tool Clear DTC Information function.

DIAGNOSTIC AIDS

NOTE:
^ Refer to HO2S wire repair notice in Service Precautions.
^ Refer to Connector Test Adapter kit J 35616-A Notice in Service Precautions.

For intermittent conditions, refer to Symptoms. Intermittent Conditions

TEST DESCRIPTION

Steps 1 - 3:

Steps 4 - 10:

The numbers below refer to the step numbers on the diagnostic table.
5. Check the HO2S bank 1 sensor 1 wiring, the PCMs response. With the harness connector terminals jumpered together, the scan tool should display an HO2S bank 1 sensor 1 voltage below 75 mV.
9. This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.