Mineral scale buildup on the heating element is the most probable cause. It hinders performance and can cause unusual sounds.
Fix: Descale the brewer immediately.
- Get 8 ounces of undiluted white vinegar and a 10 oz ceramic cup (not paper).
- Fill the Hot Water Tank with the vinegar to the FILL LEVEL mark.
- Place the cup on the drip tray, close the lid. Run a brew cycle without a K-Cup.
- Pour the hot vinegar from the cup back into the tank.
- Start another brew cycle, but turn the power off just after it starts dispensing. Let it sit for 30 minutes.
- After 30 minutes, run a brew cycle to empty the tank into the sink.
- Fill the tank with 8 oz of bottled water. Run a water-only brew cycle. Repeat this rinse cycle three times.
If that didn't work: After two descale attempts with no improvement, the unit requires service. Contact Keurig Customer Service at 1-866-901-BREW (2739). No user-serviceable parts are inside.
Heads up: Descaling every 3-6 months is required for optimal performance, more often if you have hard water. White deposits in the tank are a clear sign.