On my kia the brake light is on and I don't have any brakes the fluid is perfectly fine

SOURCE: kia brake prob.

It's probably leaking behind the master cylinder and into the brake booster. If you have a manual transmission, it can also be leaking from the clutch, but it's probably the master cylinder. I just replaced this in mine. Check to see if any is leaking down the back of the firewall. You could loosen the bolts that hold the master to the booster and see if anything leaks out from behind there. If it does replace the master. Not hard to do yourself, just bench bleed the master cylinder and rebleed the brakes when you're done. It's also a good idea to replace the front pads at the same time, or you'll push the contaminated fluid into the new master the next time you do it.

SOURCE: 2006 Kia Sorento Brake Lights not working

Apparently this is a recall matter and will be fixed at no charge. KIA Consumer Assistance Center 1-800-333-4542. Recall notices were to go out in May/June 2009.

SOURCE: losing brake fluid(2001 kia sportage)

Check the rear wheel cylinders if you have drum brakes on the rear. Check the master cylinder cap to be sure it's on right & snug. Use D.O.T. 3 fluid,not synthetic. If you're losing fluid there's a reason. Check the front brake pads & slides for the calipers,could be frozen with rust & eating up the pads. Fluid would seem low if the pads are shot.

SOURCE: brake lights not working, fuse

Check the brake switch above and behind the brake pedal. It may have slipped out of position or could be faulty. It can be tested with a meter.

SOURCE: 2001 kia sportage brake fluid leak problem

kia s leak is common in the proportioning valve located on the fire wall two line from the master cylinder to the pv then 4 lines comming out, Ther eic two hew nuts on the top of the valve. Simply look at the one that is wet take a 16 mm ratchet and take off the hex nut. Now there are two different set ups in this nut but the fix is the same. Rplace the bottom o ring. On one of the set ups it has a small cover dont lose it the o ring is under this cover