I have a single handed Kohler Vinnata kitchen faucet that is leaking from the handle. Cartridge has been replaced and hasn't stopped leak. What now?

yes there is an o-ring to prevent leaking

William, you or a plumber will have to replace the cartridge and seals to stop the leaks. The parts may have life time warranty, check your manual if you still have it. Check the attached links,instruction and guides, Good luck
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KOHLER Canada Warranty Information Planning
Maintenance Replacement Parts KOHLER
Fort single control pullout kitchen sink faucet with color matched...
Kohler kitchen faucet repair

Replace the cartridge

you must use genuine kohler parts,if you got something from lowes or home depot that was some other brand they usually leak. also look for calcium build up inside the valve body,you can use 1500 grit wet sand paper to remove it just be carefull and dont sand too much,then apply water proof plumbers grease inside the valve body befor you install the new cartridge.

The handle has a allen set screw loosen that until the handle comes off then the bonnet nut will unscrew revealing the bonnet cap and washer the cartridge should be under that most kohler's require a special tool to remove cartridge(turn water to faucet off prior to working on faucet,also note how everything is removed it needs to be replaced in same order especially the cartridge,also you should use plumbers grease to coat all seal when replacing everything).

gently tap up on it calcium is holdin place cartridge under handle

Kohler K-79402-CP aerator kit
Kohler K-78250
Kohler 1001100
You might try to replace aerator on end of spout if water is leaking around it, or you might try to replace cartridge. VALVE (CORALAIS AND FAIRFAX)
K-GP77548
$14.80 List Price

Call Kohler if you need more info.

Remove top handle and lock nut and remove plastic cartridge buy the cartridge it has detailed instructions better yet call 1-800-4-KOHLER and they will mail you a free replacement

You need to remove handle and cartridge and spout should come off to replace the rest very common leak

You need to call 1-800-4-KOHLER and get a replacement cartridge