Lynnes Hyundai

I am a second owner of a 2011 Hyundai Sonata. The check engine came on with 19K miles. First, I went to my reliable mechanic and told me it's the gas sensor but good news is because it's under warranty, I can take it to any Hyundai dealer to get it fixed for free since it's under 5 yrs, and below 60K. The lady I talked to in the service dept. told me right off the butt, that they don't honor other diagnosis other than their service guys and it'll cost me already $120 just for diagnostic! Then they will let me know if the parts or whatever service they will do is under warranty! These people will do anything to find fault to a car so they can make money!