P0134

DTC P0134 Oxygen Sensor 1 (O2S1) No Activity or Open

Circuit Diagram:

Circuit Description
The Engine Control Module (ECM) supplies a voltage of about 0.45 volts between terminals M12 and M29 (if measured with a 10 megohm digital voltmeter, this may read as low as 0.32 volts). The Oxygen sensor 1 (O2S1) varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volts if the exhaust is lean.

The sensor is like and 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 O2S1 pigtail wiring, connector, or terminal is damaged, the entire O2S1 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 O2S1 wire(s). Any attempt to repair the wires, connector or terminals could result in the obstruction of the air reference and degrade the O2S1 performance. Refer to DTC P0131.

Conditions for Setting the DTC
- O2S1 voltage is stuck between 300 and 600 mV.
- Engine Coolant Temperature (ECT) is greater than 60 °C (140 °F)
- System voltage is greater than 10 volts.
- Engine run time is greater than 60 seconds.
- Airflow is greater than 1 g/sec.
- DTCs P0106, P0107, P0108, P0117, P0118, P0122, P0123, P0171, P0172, P0201, P0202, P0203, P0204, P0300, P0336, P0337, P0351, P0352, P0401, P0402, P0404, P0405, P0406, P0502, P0506, P0507, P1404, P1441, and P0443 are not set.
- 3 second delay after exiting Decel Fuel Cut-off (DFCO) mode.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM 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.
- The vehicle will operate in Open Loop.

Conditions for Clearing the MIL/DTC
- The MIL will turn off after four 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.
- The DTC(s) can be cleared by using the scan tool.
- Disconnecting the ECM battery feed for more than 10 seconds.

Diagnostic Aids
- Normal scan tool voltage varies from 150 mV to 850 mV while in Closed Loop. If DTC P0134 is in intermittent, refer to Intermittents.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. The On-Board Diagnostic (OBD II) 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 O2S1 should warm up, and its voltage output should vary between 150 mv and 850 mv. When the O2S1 voltage varies, the engine will go into Closed Loop. This determines if the O2S1 1 is operating properly.
4. This will determine if the sensor is malfunctioning or if the wiring or the ECM is the cause of the DTC P0134.
6. Use only a high impedance digital voltmeter (DVM) for this test. The test checks the continuity of the O2S1 signal and the ground circuits; if the ground circuit is open, the ECM voltage on the circuit will be over 0.6 volts (600 mv).
10. The replacement ECM must be reprogrammed. Refer to the latest Techline procedure for ECM reprogramming.

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