My Sonata wont start when it has run for sometime but when it cools it start right up ???
Jose check the fuel pressure when the car is hot and up to temp, It seems to be fuel related.
Sounds like vehicle is vapor locking have vehicle put up on a lift and check to see it the heat shield is missing this is a piece of metal that goes between the exhaust system and the gas tank. If this is missing after vehicle heats up the heat from the exhaust will cause the gas in the tank to vapor lock.
Or worn bushings in the starter if they still have bushings some have bearings and if dry heat up and expand, Check fuel issues first.
When it won't start, see what you don't have. Spark or fuel. Spray some starting fluid down the throttle body. It should run a few seconds on the starting fluid. If so, it's a fuel problem, as described above. If not it's an ignition (no spark) problem. If you don't have spark it's probably going to be the ignition control module. They'll sometimes get hot and quit but work fine when cold. HTH. -Jim
Looking for a Used Sonata in your area?
CarGurus has 49,188 nationwide Sonata listings starting at $700.
Search Hyundai Sonata Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Hyundai Sonata Experts