You can do a binnacle test, Hold down the mileage reset button with the ignition off, turn the ignition key to position 1, Wait for TEST to appear and then release reset button, watch as the binnacle does a self test.
As for sensor it can be checked with a multimeter set on ohms.
ok changed the sensor still a no go. been through and check all the connection as much as possible. it has to be something around the engine config as im suffering with the tach not working and the avg fuel gauge under thats not working.