Code P0134, Heated Oxygen Sensor Open Circuit: Notes

PCM supplies and monitors voltage of about .45 volt between PCM sensor low reference circuit (Tan wire) and sensor signal circuit (Purple wire). If read with a 10-megohm DVOM, voltage may read as low as .32 volt. Sensor varies voltage within a range of about one volt (rich) to .10 volt (lean). Sensor is like an open circuit and produces no voltage when less than about 600°F (316°C). Open loop operation is caused by open oxygen sensor circuit or a cold sensor. Code P0134 will set when the following conditions are present.

• Engine coolant temperature is greater than 110°F (43°C).
• Engine run time is more than 40 seconds.
• Sensor signal voltage is steady at .35-.56 volt.
• Throttle angle is greater than 3 percent.
• All conditions are met for about 30 or more seconds.
  NOTE: Test numbers refer to numbers on diagnostic chart.

1. If conditions necessary to set Code P0132 exist, system will not go into closed loop.
2. This will determine if sensor or wiring is cause of Code P0134.
3. This test checks continuity in reference circuit.