"speedometer sometimes work,at times it does not"に関する回答Check the grounds for the dash panel. Also, unplug, clean and replug the various plugs leading from the dash panel to the rest of the car. If you notice any that seem sloppy (loose), have burned places, or are heavily corroded, replace them.
"Tire Pressure Light is on even though the tires don't need air."に関する回答The sensors contain batteries that are good for 3-5 years, depending on the units used. This is a nearly universal design element - all makes and models. Take it to a reputable tire shop to have the batteries replaced.