I have a tankless water heater and in the past month my kitchen sink has been pulsating, so the tankless water heater will not send hot water to the kitchen sink, and only the kitchen sink. It has run fine for 4 years with no problems. Nothing in the house has changed. If I run the dish washer and turn on hot water tap I get hot water, but when dish washer goes off so does the hot water. Need help this is frustrating :(

What type of faucet do you have> One handle or two knobs? Back to you. Tom

2 knobs

Sounds like seat chatter to me. The solution would be to shut off the hot water supply and unscrew the bonnet packing nut located under the knob. Now back the stem and washer assembly out counterclockwise. Check the washer and replace if worn. Tighten the screw that loosened up allowing the washer to vibrate every time you ran water. Reassemble and rest. Better now? Good luck, bTom