If you mean the transmission input or output speed senors (called pulse
generators a/b respectively by Hundai), you will need to follow the two
separating wires coming from the blue connector under the battery tray to
the corresponding sensors. One sensor is located under the brake master
cylinder, the other is on the front side of the transmission. Remove the bolts (10mm head) securing the sensors and install opposite of removal. If your arms are small enough you won't need to remove anything to replace the sensors.
If the VSS is defective replace the instrument cluster.
Hyundai accent idle speed
The top speed of an Accent is approximately slow.
The 2003 Hyundai Accent has a 5-speed manual.
The 2005 Hyundai Accent has a 5-speed manual.
The 2006 Hyundai Accent has a 5-speed manual.
The 2011 Hyundai Accent has a 5-speed manual.
The 2010 Hyundai Accent has a 5-speed manual.
The 2001 Hyundai Accent has a 5-speed manual.
The 2013 Hyundai Accent has a 6-speed manual.
The 2012 Hyundai Accent has a 6-speed manual.
The 2002 Hyundai Accent has a 5-speed manual.