Hello All - This is my first time posting on this site. I have been a fan for CarTalk for many years.
I have a 2013 Hyundai Sonata GLS 2.4L Engine and recently replaced the Battery and Spark Plugs myself. My car has 55,000 miles and I have had all the normal maintenance performed. The maintenance guide suggested the plugs be replaced at 45,000 miles I waited until 55,000 as I was not having any problems. The last couple of trips to auto shop showed the battery slowing losing the ability to retain a charge so it thought might as well replace now rather than later.
After changing the battery and plugs I went to fill up my Car with Gas and the MPG dropped. Normally when I fill up the car with gas the dashboard of my car would show 420 miles until empty. Recently when I filled up the car it showed 370 miles until empty. I am thinking this is due either to replacing the battery and having the computer reset or I set the gap on one or more plugs wrong. The car is not misfiring so I am thinking it is the replacement of the battery and resetting the computer. I was going to run the care for a couple of tanks and see if the MGP change. I am also going to monitor the mileage and see if it matches the overall MPG.
Is my thinking about the battery and computer resetting correct? Any other thoughts.
Thanks in advance for any and all replies.