Kenmore Dishwasher Temperature Off? Causes & Fix
Most likely your incoming water is too cool, because a Kenmore dishwasher's heater is a boost system that expects hot water to arrive — it cannot make up a cold supply. Beyond that, a drifting thermistor or a heater relay welded on are the internal causes of water that runs too cool or too hot.
Why temperature drives cleaning#
Wash temperature sets cleaning power, sanitizing, and drying, and Kenmore regulates it through a thermistor feeding the control board, which switches the heating element. Kenmore builds these on two platforms — the Whirlpool 665 and the LG 630 — that sense and heat slightly differently, but both depend first on hot water actually reaching the machine.
Causes at a glance#
| Likely cause | What you'll notice | How common | First move |
|---|---|---|---|
| Low incoming water temp | Cool washes, poor drying | Most common | Run the sink hot first |
| Thermistor reads low | Overheats past target | Common | Test the thermistor |
| Thermistor reads high | Underheats, weak cleaning | Common | Test the thermistor |
| Heater relay stuck on | Overheats (Whirlpool 665) | Occasional | Inspect the control board relay |
| Water heater set high | Water too hot, over 170°F | Occasional | Lower the water heater setting |
Do You Have the Right Tools?
Water pressure gauge ($60), spray arm tester, float switch multimeter ($85), and drain inspection camera. Our technician arrives with $3,000+ in professional tools — your diagnostic is free.
Licensed & Insured · 90-Day Warranty · Same-Day Service
Working through the causes#
Low incoming water temperature (most common). The dishwasher heater only boosts; it expects a hot supply to arrive and cannot recover from a cold first fill. Run the kitchen tap until it is hot before starting so the opening fill is warm. The wash needs to reach about 120°F to clean well. Thermistor reading low (common). If the thermistor tells the board the water is 90°F when it is really 150°F, the board keeps heating well past target and the water runs too hot. On both platforms a thermistor that is out of calibration is tested and replaced. Thermistor reading high (common). The opposite drift makes the board think the water is hotter than it is, so it stops heating early and the wash never reaches temperature, leaving weak cleaning. Again the fix is testing and replacing the thermistor. Heater relay stuck on (occasional). On the Whirlpool 665 platform, a heater relay welded shut on the control board sends continuous power to the element, overheating the water. A board with a stuck relay is replaced. Water heater set high (occasional). If your household water heater is set to 140°F or higher and the dishwasher boosts on top of it, the wash can approach 170°F to 180°F. Lower the water heater to a safer setting.
Verify the wash temperature#
- Run the kitchen hot tap until it is hot, then start a normal Kenmore cycle.
- For a rough check, run a Normal cycle with no dishes and open the door mid-wash to feel the steam.
- Confirm your sanitize cycle can hold water at 150°F, which it must reach to sanitize.
- If the water is scalding, check the water heater setting before suspecting the dishwasher.
- If it stays cool with hot water supplied, test the thermistor and heater circuit.
Safety First — Know the Risks
Live 120V wiring in a wet environment is one of the most dangerous DIY scenarios. Water + electricity = serious shock risk. Our techs are licensed and insured — let them handle the risk.
Licensed & Insured · 90-Day Warranty · Same-Day Service
Repair or replace?#
A thermistor or heater relay is an inexpensive repair beside a new machine, so on a Kenmore dishwasher under roughly eight to ten years old, fixing the temperature fault is well worth it.
Preventing a repeat#
- Run the kitchen hot tap before each cycle so the opening fill arrives warm.
- Keep your household water heater at a safe setting rather than pushing it high.
- Use the sanitize cycle when you need the hottest wash instead of overheating every load.
- Clean the dishwasher periodically so scale does not insulate the heating element.
- Have the thermistor tested if cleaning and drying results drift over time.
Wash water too hot or too cool? Our technicians service Kenmore dishwashers same-day across Sacramento and the Bay Area. Book your repair.
Appliance Repair Technician · 11 years experience
Experienced technician with 11 years specializing in Frigidaire and Electrolux refrigerator and dryer repair with a focus on safety.
