P0134

CIRCUIT DESCRIPTION
The heated oxygen sensor (HO2S) is a sensor used to detect oxygen-content in the exhaust. The powertrain control module (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. In order to correct for rich or lean conditions, the PCM adjusts the injector pulse width. This DTC indicates that the HO2S voltage remained at or near the bias voltage for a calibrated period of time.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0201- P0208, P0410, P0412, P0418, P0419, P0440, P0442, P0443, P0446, P0449, P1133, P1415, P1416, or P1441 are not set.
^ The system voltage is between 9-18 volts.
^ The engine is running for 200 seconds.
^ The exhaust gas recirculation (EGR) flow diagnostic test is not active.
^ The catalyst diagnostic test is not active.
^ The secondary air injection (AIR) diagnostic test is not active.

CONDITIONS FOR SETTING THE DTC
HO2S signal voltage remain within 400-500 mV for approximately 1 minute.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS

NOTE: Refer to Heated Oxygen Sensor (HO2S) Wire Repair Notice in Service Precautions.

For intermittent conditions, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-8:

Steps 9-13:

The number below refers to the step number on the diagnostic table.
5. If the voltage displayed on the scan tool changes from near bias to above 1,000 mV, the HO2S bank 1 sensor 1 may be shorted to the HO2S heater low control circuit. This condition will only occur with the key ON, engine OFF or when the engine is running and the bank 1 sensor 1 heater is commanded OFF.