sensors
    car
    truck
    rv

    Oxygen (O2) Sensor

    Measures exhaust oxygen so the ECM can fine-tune fuel mix and protect the catalytic converter.

    Replacement
    $250–$600
    Labor
    0.5-1.5 hrs
    Lifespan
    60,000-100,000 miles

    How it works

    A zirconia or wideband cell generates voltage based on exhaust O2 content. Upstream sensor controls fueling, downstream sensor monitors cat efficiency.

    Symptoms of failure

    Check-engine light (P0130-P0167)
    Drop in fuel economy 15-40%
    Failed emissions test
    Rough idle
    Sulfur smell

    How a shop diagnoses it

    1. 1.Read live data: upstream should cycle 0.1-0.9V; downstream nearly flat ~0.7V.
    2. 2.Inspect for oil or coolant contamination.
    3. 3.Compare bank 1 vs bank 2 readings.

    Common brands

    Denso
    NTK / NGK
    Bosch
    Walker

    Recommended for this repair

    unknown
    truck

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    Frequently asked questions

    How much does a oxygen (o2) sensor cost to replace?

    Replacement runs $250–$600 including parts and 0.5-1.5 hours labor. Exact cost depends on vehicle, parts tier (OEM vs aftermarket), and local labor rate.

    How long should a oxygen (o2) sensor last?

    Expected lifespan is 60,000-100,000 miles. Driving conditions, climate, and maintenance affect real-world life.

    What are the symptoms of a failing oxygen (o2) sensor?

    Check-engine light (P0130-P0167); Drop in fuel economy 15-40%; Failed emissions test; Rough idle; Sulfur smell.

    Can a oxygen (o2) sensor be repaired or only replaced?

    Most modern oxygen (o2) sensors are sealed units that get replaced rather than rebuilt. A shop will diagnose, confirm with a load or output test, then swap the unit and verify operation.

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    Sources & references

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