The iridium tipped OEM spark plugs of a 1st generation (2012, 2013, 2014, 2015) GM Chevy Sonic should last up to 100,000 miles. But they should be checked several times before that mileage to make sure the Ecotec A18XER motor is running properly. Take a look at my DIY tutorial for the procedure by clicking on the text link or thumbnail picture below.
Chevrolet Sonic Engine Spark Plugs Replacement Guide
