Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Code P0134, Heated Oxygen Sensor Open Circuit: Notes
Control module supplies and monitors voltage of about .45 volt between control module HO2S low reference circuit and HO2S signal circuit. If read with a 10 megohm DVOM, voltage may read as low as .32 volt. HO2S varies voltage within a range of about 1 volt (rich) to .10 volt (lean). Sensor is like an open circuit and produces no voltage when less than about 600°F (360°C). Open loop operation is caused by open oxygen sensor circuit or a cold sensor. Code P0134 will cause system to operate in open loop. Control module will illuminate Malfunction Indicator Light (MIL).
- If conditions necessary to set Code P0132 exist, system will not go into closed loop.
- This will determine if sensor or wiring is cause of Code P0134.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.