Q:

What does engine code P0171 mean?

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Quick Answer

Engine code P0171 means that an oxygen sensor in a vehicle’s engine has detected too much oxygen in the exhaust. It is often caused by intake air leaks, faulty fuel injectors and exhaust gas leaks.

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Full Answer

Code P0171 is one of the more common trouble codes. An internal oxygen sensor triggers this code when it senses too much air in the system. The sensor provides a reading of the air/fuel ratio leaving the engine's cylinders.The vehicle's powertrain/engine control module uses that reading and adjusts to keep the engine running at that optimum ratio. If the ratio cannot be maintained and there is too much air, it triggers this code.

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Related Questions

  • Q:

    How do you replace an O2 sensor?

    A:

    To replace an oxygen sensor, loosen the sensor with a specially designed wrench, and enlist the help of a breaker bar to remove the sensor entirely. You need a high-quality penetrant spray, an oxygen sensor wrench, a breaker bar and a screw-type oxygen sensor.

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  • Q:

    Do all vehicles have oxygen sensors?

    A:

    Virtually every vehicle manufactured since 1980 has an oxygen sensor, according to HowStuffWorks. Most cars on the road actually have between two and four sensors, according to John Nielsen, the director of engineering for the American Automobile Association, as reported in an article on Edmunds.com.

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  • Q:

    How does an oxygen sensor in a car work?

    A:

    The oxygen sensor is positioned inside in the exhaust pipe, and it is used to detect rich or lean mixtures. This sensor is an essential component in the emissions control system, and it transmits data to the engine's computer. The primary function of the oxygen sensor is to help the engine operate as smoothly as possible by detecting the appropriate air-to-fuel ratio and using fuel efficiently.

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  • Q:

    How do you replace your vehicle's oxygen sensor?

    A:

    To replace the vehicle's oxygen sensor, lift the car, locate the sensor, disconnect the sensor wire, remove the bolts that attach the sensor to the exhaust system, remove the old sensor, bolt the new sensor in the place, and reconnect the sensor wire. Lower the vehicle to complete this process.

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