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. To correct for rich or lean conditions, the PCM adjusts the injector pulse width.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416, or P1441 are not set.
^ The system voltage is between 9-18 volts.
^ The engine is running for 3 minutes.
^ The EGR flow diagnostic test is not active.
^ The catalyst diagnostic test is not active.
^ The AIR diagnostic test is not active.

CONDITIONS FOR SETTING THE DTC
HO2S bank 1 sensor 1 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.
^ Use a scan tool in order to clear the MIL and the DTC.

DIAGNOSTIC AIDS

NOTE:
^ Refer to Heated Oxygen Sensor (HO2S) Wire Repair Notice in Service Precautions.
^ Refer to Connector Test Adapter Kit J 35616-A Notice in Service Precautions.

Check for the following:
^ Inspect harness connectors for backed out terminals, for improper mating, for broken locks, for improperly formed or damaged terminals, and for poor terminal-to-wire connections. Refer to Testing for Intermittent and Poor Connections in Diagrams.
^ A damaged harness-Inspect the wiring harness for damage. If the harness appears OK, observe the scan tool while moving connectors and the wiring harnesses that are related to the HO2S bank 1 sensor 1. A change in the display will indicate the location of the malfunction. Refer to Testing for Intermittent and Poor Connections in Diagrams.
^ For intermittent conditions, refer to Symptoms - Computers and Control Systems. Symptom Related Diagnostic Procedures

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may assist in diagnosing the condition. The information may help determine how often the condition that set the DTC occurs.

TEST DESCRIPTION

Steps 1-8:

Steps 9-14:

The numbers below refer to the step numbers on the diagnostic table.
2. When the system is operating correctly, the HO2S voltage should toggle above and below the specified values.
5. The specified value is what is measured on a correctly-operating system.
6. The specified value is what is measured on a correctly-operating system.
12. This vehicle is equipped with PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.