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Thermador Dishwasher Not Cleaning Well? This Could Be Why

In keeping with the brand’s reputation, a Thermador dishwasher provides superior performance and reliability. So, what could be the problem if you find your Thermador dishwasher not working as well as you expect? First, make sure your home’s water supply is functioning properly and that you’re using the right detergent in the right amounts. Troubleshoot a Thermador dishwasher not cleaning well with these causes and solutions.

Troubleshooting a Thermador Dishwasher Not Cleaning Well

While part malfunctions are always possible, the most common reasons for a Thermador dishwasher not cleaning well usually have a simple answer. We’ll discuss the most likely causes, many of which have DIY fixes.

1. Problem With Water Supply

Thermador dishwasher troubleshooting actually begins outside the dishwasher with your home’s water supply. Performance can be affected by several water supply issues.

Here’s how to evaluate your water supply when your dishwasher leaves dishes dirty:

  • Check the water temperature: Hot water should reach a temperature of 120-150℉ to optimally clean dishes. Test your home’s hot water with a thermometer and adjust your hot water heater as needed.
  • Assess for hard water: Hard water has a higher mineral content that can leave residue on dishes. Try using more rinse aid to dispel the residue. If that doesn’t work, you may want to consider a home water softening system.
  • Inspect the water inlet valve: This valve opens and closes to let water enter the dishwasher as needed. If it’s malfunctioned, the dishwasher may not have enough water to clean dishes. A broken water inlet valve requires replacement.

2. Not Using Dishwasher Correctly

How do I get my dishwasher to clean better? Make sure you’re using the right detergent amounts and the right wash settings. Check your owner’s manual to determine the right setting for your particular wash load, selecting a longer wash for more heavily soiled dishes. Your user manual can also give recommendations on the right amounts of detergent to use with each load.

Lastly, one of the most important dishwasher loading tips is to avoid overcrowding when loading. Make sure each item is properly inserted in its slot and not nesting with other dishes or cutlery, improving access to water and detergent. Overcrowding can also limit airflow, causing your dishwasher to leave dishes wet after a wash cycle. Make sure there is adequate space between loaded items so they can dry properly.

thermador dishwasher not cleaning well

3. White Spots On Clean Dishes

Is your Thermador dishwasher leaving residue behind that looks like white spots on dishes? This may be due to hard water or etching. If your home has hard water, it may be necessary to use more rinse aid with each wash cycle. Some dishwashers may also require additional salt for their built-in water softening systems.

Etching occurs when the surface of glassware erodes, resulting in pitting or scratching. Though etching is permanent, it can be prevented by skipping a pre-rinse. It also helps to wash glassware on a light setting with the recommended amount of detergent.

4. Spray Arm Malfunction

 Regular cleaning of the spray arms is one of the most important dishwasher maintenance tips that improve performance. If the small holes on each spray arm are blocked, water won’t be able to emerge and properly wash and rinse each item. Remove each spray arm and rinse it under running water, using a toothpick to dislodge any blockages in the holes before replacing.

thermador dishwasher troubleshooting

5. Dishwasher Detergent Issues

Believe it or not, your detergent may be responsible if your Thermador dishwasher doesn’t clean dishes sufficiently. 

These dishwasher detergent issues can negatively affect performance:

  • Too little detergent: Not adding enough detergent can leave dirt and grease on dishes.
  • Too much detergent: Using too much detergent can leave behind a sudsy residue that leaves dishes streaked or spotty. Refer to your user manual to determine the right detergent amounts for your wash load.
  • Using the wrong detergent: Make sure you only use detergent formulated for dishwashers, not dish or hand soap. Thermador recommends using a powder form of detergent for optimum performance.
  • Faulty detergent dispenser: Check the dispenser to make sure it isn’t blocked and opens and closes properly to release detergent. A faulty dispenser requires replacement.


Is your Thermador dishwasher not cleaning well even after these troubleshooting tips? You may need a professional dishwasher repair service to assess the problem. Call Best Service Company for a thorough evaluation.

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