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Q: engine light on

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I had my mass flow change and now im told my o2 sensor need to be change. not sure what to do

Hello...What to do depends on whether the person examining the car actually tested the oxygen sensor (O2 sensor) or not. That "part", the O2 sensor, has no doubt been mentioned to you because it appeared in a list of possible faults in a Diagnostic Trouble Code that was downloaded by the mechanic because you told him or her that your check engine light came on. But, unless the O2 sensor ITSELF was actually tested, there is no way of determining if that component is the faulty "one" and thus caused the check engine light to illuminate. So, to answer your question, the thing to do is ask the mechanic if he actually tested the O2 sensor ITSELF or if he or she is just simply guessing at that component out of a longer list of possible faults that are identified in the CODE that he or she downloaded. If it’s a "guess", certainly you can go along with that and try it out but "guessing" is almost never the least cost and most technically proficient way to repair a motor vehicle. The bottom line is so long as a valid and complete, and accurate diagnostic was done a la what is required in the Factory Service Manual for your vehicle you will be in fine shape. If that was not done, you should seek the services of a competent mechanic. If you elect to use the services of YourMechanic’s mobile U.S. network of experts, in your case you should request a check engine light diagnostic and the responding certified mechanic will simply get this resolved for you according to the principles that I just stated. Please do not hesitate to contact us with follow up questions or additional concerns, as we are always here to help you.

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