Quick Answer: Why Your LG Dishwasher Won't Heat the Water#
Most likely: the tub-floor heating element has burned out — it is behind nearly half of HE errors — or the thermistor is feeding the board a false "hot" reading so it never fires the element. One LG-specific point saves confusion: this element heats the wash and rinse water only; it does not dry the dishes, because LG uses its Dynamic Dry air-and-door-crack system instead. So a heating failure shows up as greasy dishes and failed Sanitize cycles, not wet ones. An HE code is the board's way of saying the water is not warming despite the element being commanded on.
Likely Causes at a Glance#
| Cause | Likelihood | What to check |
|---|---|---|
| Heating element failure | Most likely (~45%) | element reads 12-15 ohms; open (infinite) means burned out |
| Thermistor failure | Common (~25%) | ~50K-55K ohms cold; false readings give cold water with no HE code |
| Control board relay | Occasional (~15%) | element and thermistor good, but no 120V at the element during heating |
| Wiring / connection failure | Occasional (~10%) | blackened or melted spade terminals at the element |
| Incoming water too low | Rare (~5%) | supply below 100F can trip HE; run the hot tap first |
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.
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Walking Through the Diagnosis#
Confirm the water really is not heating. Run a Normal cycle, pause it about fifteen minutes in during the main-wash heating phase, and briefly touch the water at the tub bottom — it should feel clearly hot, not just warm. Barely-above-supply temperature confirms a heating failure. LG's element heats to roughly 140-155F on a normal wash and up to 160F on Sanitize, so a wash that seems fine while Sanitize fails points to an element with increased resistance — heating a little, but not enough.
Now meter the parts with the breaker off. Reach the element terminals through the kick panel (four Phillips screws) and measure across them: about 12-15 ohms is healthy, an infinite reading means it has burned out, and 25-plus ohms means a partial failure. Check each terminal to the tub for a ground fault — any reading there is a safety issue. The thermistor in the sump should read about 50K-55K ohms cold, dropping toward 5K-8K ohms near 140F; infinite or fixed resistance means it has failed, and note that a bad thermistor produces cold water with no HE code because the board wrongly believes the water is hot. If both test good, carefully verify 120V at the element connector during the heating phase — no voltage there is a control-board relay fault. Inspect the spade connectors for blackening too, and if everything checks out, run the hot tap before starting: supply water below 100F can itself trip HE. LG's ThinQ Smart Diagnosis is handy here, logging thermistor readings and heating commands over the cycle.
How to Prevent This#
Cut mineral buildup on the element with a monthly dishwasher cleaner or a water softener — hard water (10-17 grains locally) creates hot spots that corrode the element. Run the kitchen hot tap before starting so pre-heated water reaches the tub, and keep the dishwasher on a surge-protected circuit to shield the board's heating relay.
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.
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Repair or Replace? The Short Version#
An element or thermistor is a low-cost, targeted part on a dishwasher that otherwise runs, so this never approaches a replacement decision. The trickiest case is the no-code thermistor fault, which is exactly where the meter earns its keep. If you would rather not probe a live 120V connector, our technicians carry LG elements and thermistors and confirm the fault first — book a same-day visit.
Frequently Asked Questions#
Why are my dishes greasy after an LG cycle?#
Grease cannot emulsify in cold water, so a failed heating element leaves a greasy film even when the cycle completes. Note that LG's element heats the wash water, not the drying phase, so this is a wash-temperature problem.
What does the HE code mean?#
HE means the control board commanded heat but the water temperature is not rising as expected. It usually points at a burned-out element or the wiring to it, though supply water below 100F can trip it too.
My water is cold but there's no HE code — how is that?#
A failed thermistor can report "hot" when the water is actually cold, so the board never fires the element and never flags an error. Test the thermistor for about 50K-55K ohms cold; a fixed or infinite reading confirms it.
Does the heating element affect drying on an LG dishwasher?#
No — LG uses Dynamic Dry (air circulation plus an automatic door-crack), so the element serves only wash and rinse heating. A heating failure hurts cleaning and Sanitize, not drying.
Senior Appliance Repair Technician · 15 years experience
EPA-certified technician with 15 years of experience specializing in refrigerator and cooling system repairs.
