Smeg Dishwasher H3 Error Code: Causes and Fixes
Quick answer: Heater not reaching target
What you’ll notice
Water does not reach wash temperature; heater response is below threshold.
Smeg
Dishwasher
Code H3
high severity
Smeg models: Smeg dishwashers have a stainless-steel tub interior. The filter is in the centre of the tub floor, twist-out. The retro colour finishes (Cream, Pastel Blue, Pink, etc.) are cosmetic — the internal components are identical across all SMEG dishwasher colours and finishes.
Common causes
- Heating element failed or heavily scaled
- NTC sensor inaccurate
- Incoming water temperature very low in winter
Step-by-step fix
- Run a descaling cycle with citric acid or a dishwasher descaler.
- If the problem persists, test the heater element with a multimeter — it should show a resistance of around 20–30 Ω.
- Check the NTC sensor resistance.
Tools you may need
MultimeterDescaling agent
Prevention
- Descale in hard-water areas every 3 months.
- Connect the dishwasher to the hot water supply where possible.
When to stop DIY
Replace the heater element or NTC sensor if testing shows a fault.
FAQ
What does H3 mean on Smeg dishwasher?
H3 usually indicates: Heater not reaching target.
Can I keep using the appliance with H3?
Use caution. Severity is high. Replace the heater element or NTC sensor if testing shows a fault.
How long does this fix usually take?
Typical first-pass troubleshooting takes 60 minutes (descale); 30 minutes (component test).