TSB - SERVICE ACTION: SPARK PLUG REPLACEMENT (SA342) - This bulletin provides the procedure to replace the spark plugs on some 2018MY Forte (YDm), produced from November 21, 2017 through April 12, 2018, and 2018MY Rio (SC) vehicles, both produced from November 22, 2017 through February 6, 2018, which may exhibit a malfunction indicator lamp (MIL) ON with DTCs P0300 through P0304 due to the spark plug porcelain cracking during manufacturing. Follow the procedure outlined in this bulletin to replace all four spark plugs, whether or not the MIL is ON.
