Your speed sensor might be broken. Check it for rust or broken plastic part that would let water get in. Usually means you need to replace.
The 2001 Hyundai Elantra's came with the 2.0L engine
The 2001 Hyundai Elantra has an inline 4 engine.
The 2012 Hyundai Elantra has an inline 4 engine.
The 2014 Hyundai Elantra has an inline 4 engine.
The 2007 Hyundai Elantra has an inline 4 engine.
The 2010 Hyundai Elantra has an inline 4 engine.
The 2008 Hyundai Elantra has an inline 4 engine.
The 2001 Hyundai Elantra's came with the 2.0L engine
The 2006 Hyundai Elantra has an inline 4 engine.
The 2011 Hyundai Elantra has an inline 4 engine.
The 2003 Hyundai Elantra has an inline 4 engine.
The 2002 Hyundai Elantra has an inline 4 engine.