REPLACEMENT RADIATOR CAP : The radiator cap holds the coolant inside the radiator, but it also works as a two-way valve that keeps the right pressure inside so the radiator does it work correctly. If the pressure isn't maintained, the coolant can boil and evaporate, putting the engine at risk of overheating. Symptoms of a Bad Radiator Cap: air enters the system, low coolant level, coolant leaks, overflowing reservoir, overheating engine..COMPATIBLE WITH TOYOTA, SCION VEHICLES : 2009-2016 4Runner | 2009-2012 Avalon | 2002-2006, 2009-2012 Camry | 2009-2014 FJ Cruiser | 2008-2013 Highlander | 2008-2017 Sequoia | 2007-2016 Sienna | 2008 Solara | 2009-2016 Tacoma | 2010-2017 Tundra | 2009-2013 Venza | 2009-2014 Yaris | 2012-2015 Scion iQ | 2009-2012 Scion xD radiator cap. Please check the detailed description before purchase. Thank you!.REPLACES PART # : 16401-31480, 1640131480, 16401-46610, 1640146610 radiator cap. The radiator cap can compatible with: 2007-2012 ES350 | 2006 GS300 | 2006-2007 GS430 | 2010-2013 GX460 | 2010 HS250h | 2005 IS300 | 2005-2006 LS430 | 2007-2015 RX350 | 2010-2011 RX450h | 2005-2010 SC430. Once you have a replacement and your engine is cool, simply unscrew the old cap, and install the new by screwing it on..OE FIT, FORM, FUNCTION : Professional, high quality OE style and meet or exceed all original equipment performance replacement radiator cap. Constructed with premium materials for durability. Designed to function on open cooling systems and overflow reservoir type systems and allows the cap to be installed and removed much easier..FRIENDLY NOTE : If the Radiator Cap fails on your vehicle, simply contact us for a replacement. Also if you have any other questions on our this radiator cap, please contact us at the first time. This is NOT a genuine part, it's a aftermarket replacement part manufactured by Allmotorparts.