Just bought a 2007 Hyundai Sonata. Sensor Light on drivers side is on entire time car is off, is this a problem?

This is a anti crash control, brake component can turn it on.Is the brake switch on? No okay, the ABS system has to be inspected,The dealer should be able to do that,Tell them to get the can communication wave form this will tell them if a module is communicating.

Mine was the same and having bought it second hand I thought it may have been a problem. Finally I dropped into a dealer and was told there was a factory recall on the visors. Both were changed for free next day, no dramas. Another happy customer.

My online Sonata manual shows these possibilities, but does not identify which applies specifically to 2000 Sonata.
Also, when you talk to the dealership parts counter, you'll need to know whether your 2000 Sonata is (a) 4-cylinder 2.4L MFI DOHC engine, or (b) 6-cylinder 2.5L MFI DOHC engine.
Its easy to tell - just count your spark plug wires.

-- begine excerpt from 2000 Hyundai Sonata Repair guide --

The crankshaft position sensor is located next to the flywheel.
The crankshaft position sensor is located next to the flywheel/torque converter.
The camshaft position sensor is located on the engine near the timing belt cover and under the upper radiator hose.
The crankshaft position sensor is located on the driver-s side of the vehicle, down by the lower radiator hose.
The crankshaft position sensor is located on the engine near the crankshaft pulley.
The crankshaft position sensor is located at the front of the engine near the timing belt.

--- end excerpt from 2000 Hyundai Sonata repai guide ---

more likely a fuse problem try to check the fuse boxes inside and on the engine compartment

check tyre pressure

The problem is in the tumbler(s) inside the assembly. Before you do anything, try penetrating oil to see if that works... otherwise, the entire assembly will need to be replaced.

Sounds like the mass air flow sensor. dealer tune ups include cleanig the maf sensor.

There was recall for the 2006 and 2007 Hyundai Sonata Brake Light Switch assembly. www.promanuals.net

It does.

I have a 2007 Sonata and the driver's side sun visor broke. I called the dealership where I purchased the car, and was told that they only cover it for 5 years/60,000 miles. So if your's is broken, get it in there before the warranty expires. Otherwise the cost is around $80 for the visor unit.