2005 Hyundai Sonata Owner's Manual - Page 209

DO-IT-YOURSELF MAINTENANCE 6 11 SPARK PLUGS 10.Replace the reservoir cap and check to be sure the drain cock and the radiator cap are fully closed and not leaking. G060A01NF-AAT G060B01NF-AAT Replacing the Spark Plugs The spark plugs should be changed at the intervals specified in the vehicle maintenance schedule in Section 5 or whenever engine performance indicates they should be changed. Symptoms that suggest poor spark plug performance include engine misfiring under load, loss of fuel economy, poor acceleration, etc. When spark plugs are replaced, always use spark plugs recommended by Hyundai. The use of other spark plugs can result in loss of performance, radio interference or engine damage. G060A01L CAUTION: Recheck after a few days and add the coolant if the level is below the "L" level. ! WARNING: The cooling fan is controlled by engine coolant temperature and may sometimes operate even when the engine is not running. Use extreme caution when working near the blades of the coolant fan so that you are not injured by a rotating fan blade. As the engine coolant temperature decreases, the fan will automatically shut off. This is a normal condition. 0.039 ~ 0.043 in. (1.0~1.1 mm) ! Your engine was originally equipped with Iridium-tipped spark plugs. Iridium-tipped spark plugs will last longer than conventional type spark plugs and can be identified by blue lines on the ceramic shell. NOTE: When replacing the spark plugs, always use the genuine parts recommended. Recommended Spark Plugs: Type SK16PR-A11 IFR5G-11 Remark 2.4L 3.3L NOTE: Do not clean or regap Iridium-tipped spark plugs.