P0134

CIRCUIT DESCRIPTION
The Oxygen Sensor (O2S 1) is a sensor designed to create a voltage relative to the oxygen content in the engine exhaust stream. The Powertrain Control Module (PCM) supplies the O2S 1 with high and low signal circuits. The oxygen content of the exhaust indicates when the engine is operating lean or rich. When the O2S 1 detects that the engine is operating rich, the signal voltage is high and decreases the signal voltage as the engine runs leaner. This oscillation above and below the bias voltage, sometimes referred to as activity or switching, can be monitored with the O2S 1 signal voltage.

The O2S 1 needs to be at a high temperature in order to produce a voltage. Once the O2S 1 has reached operating temperature, the controls module monitors the O2S 1 bias, or reference, voltage as well as the O2S 1 signal voltage for Closed Loop fuel control. During normal Closed Loop fuel control operation, the controls module will add fuel (enriches the mixture) when the O2S 1 detects a lean exhaust content and subtract fuel (leans-out the mixture) when the O2S 1 detects a rich exhaust condition. This DTC determines if the O2S 1 is functioning properly by checking for an adequate number of O2S 1 voltage transitions above and below the bias range of 300-600 mV. This Diagnostic Trouble Code (DTC) sets when the PCM fails to detect a minimum number of voltage transitions above and below the bias range during the test period.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0169, P0171, P0172, P0178, P0179, P0201-P0204, P0300, P0301-P0304, P0336, P0440, P0446, P0452, P0453, P0506, P0507, P0601, P0602, or P1441 are not set.
^ The air flow is more than 3 grams per second.
^ The Engine Coolant Temperature (ECT) is more than 70°C (158°F).
^ The above conditions are met for 10 seconds.
^ The Throttle Position (TP) angle is between 8-56 percent.
^ The Manifold Absolute Pressure (MAP) is greater than 25 kPa.
^ The engine run time is more than 30 seconds.

CONDITIONS FOR SETTING THE DTC
O2S 1 voltage is between 399-99 mV for 125 seconds.

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

IMPORTANT: Never solder the O2S wires. For proper wire and connection repairs, refer to Wiring Repairs or Connector Repairs in Diagrams.

Check for an exhaust leak typically within 30.5 cm (12 inches) up-stream of the O2S. Refer to Exhaust Leakage in Exhaust System. Testing and Inspection

The Intermittent Test
Use a scan tool in order to monitor this O2S 1 signal voltage. Move the related connectors and the wiring harness with a warm engine running at part throttle in Closed Loop. If the failure is induced, the O2S 1 signal voltage reading changes from the normal fluctuating voltage (above 600 mV and below 300 mV) to a fixed value around 450 mV. This may help to isolate the location of the malfunction.

An intermittent may be caused by any of the following conditions:
^ A poor connection
^ Rubbed through wire insulation
^ A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent and Poor Connections in Diagrams.

If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Diagrams.

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 O2S 1 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.