P0134

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The Powertrain Control Module (PCM) supplies a voltage of about 0.45 volt between terminals C2-22 and C2-21 (if measured with a 10 megohm digital voltmeter, this may read as low as 0.32 volt). The Oxygen Sensor (O2S 1) varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volt if the exhaust is lean.

The sensor is like an open circuit and produces no voltage when it is below 315°C (600°F). An open sensor circuit or cold sensor causes Open Loop operation.

If 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, connector or terminals. In order for the sensor to function properly, it must have a clean air reference provided to it. This clean air reference is obtained by way of the oxygen sensor wire(s). Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degrade oxygen sensor performance.

Conditions for Setting the DTC

^ DTCs P0106, P0107, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0301, P0302, P0303, P0304, P0404, P0405, P0506, P0507, P1404, P1441 not set.

^ Engine run time is greater than 30 seconds.

^ Engine Coolant Temperature (ECT) is greater than 70°C (158°F).

^ Throttle Position (TP) angle is between 9% and 56% for 20 seconds.

^ O2S 1 voltage is between 399 mV and 499 mV for 125 seconds.

Action Taken When the DTC Sets

^ The Malfunction Indicator Lamp (MIL) will illuminate.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.

^ A history DTC is stored.

^ Coolant fan turns ON.

^ Vehicle will operate in Open Loop.

Conditions for Clearing the MIL/DTC

^ The MIL will turn OFF after three 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.

^ DTC(s) can be cleared by using the scan tool.

Diagnostic Aids

Normal scan tool voltage varies between 150 mV to 850 mV (0.15 volt to 0.85 volt) while in Closed Loop. If DTC P0134 is intermittent, refer to Symptoms. Testing and Inspection

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.

2. During engine warm-up, the O2S 1 should warm-up and its voltage output should vary between 150 mV and 850 mV. When O2S 1 voltage varies, the engine will go into Closed Loop. This step determines if the O2S 1 is operating properly.

4. This will determine if the sensor is malfunctioning or the wiring or PCM is the cause of the DTC P0134.

6. Use only a high impedance digital volt ohmmeter for this test. This test checks the continuity of the O2S signal and the ground circuits; if the ground circuit is open, the PCM voltage on the circuit will be over 0.6 volt (600 mV).

8. The replacement PCM must be programmed and the crankshaft position system variation procedure must be preformed. Refer to the latest Tech line procedure for PCM reprogramming and also refer to Powertrain Control Module for the Crankshaft Position System Variation Procedure.