Johnny's Auto Center

I got a letter of a complaint [redacted] filed towards my business Johnny Auto Center. The day the vehicle came in to get serviced it was brought by someone else (male). It was also at a previous shop where she mentioned she got an oil change done. The gentleman came in with an [redacted]...

diagnostic printout and an oxygen sensor he had bought himself. He asked us how much we would charge just to install the sensor, after negotiating prices the business and the customer agreed on 50$. He later left that day and came back  the following friday and told us check engine light was back on and the printout said oxygen sensor and said we replaced the wrong one, I told him it was fine I would remove the oxygen sensor he bought and install it in the correct bank, but it would have to be the next day in the morning because I was already booked up for the day and was not able to do it. We agreed he was going to return the next day early in the morning but did not show up. He then called in the afternoon/evening time saying his engine blew and then [redacted] took over on the phone conversation and was saying the engine blew because we messed up replacing the oxygen sensor. I told her replacing an oxygen sensor does not cause an engine to blow up, she continued to say it was our fault because something was dropped in the engine that turned the oil black and blew the engine. I was trying to help her and adviced that shehas the car towed in to see what really happened, she also wanted me to pay the tow, but in my response I told her I could not do that until I saw what happened but I repeated and said an oxygen sensor would not cause an engine to blow up. She continued to say something was dropped in the engine and it blew up and I have to take responsibility and pay for the engine.