First, find out whether it's only the upper rack
- If only the upper rack is dirty, check how the dishes sit before unloading them.
- Turn the accessible spray arms by hand, then look for blocked holes, damage and a loose mount.
- If your rack has a rear water-feed connection, check that it meets when the rack closes.
- Check the filter even if only the upper rack is dirty. If both racks are dirty, check the other shared wash conditions.
When cups and bowls up top still have food on them, we'd check the loaded rack before removing anything. A dish can block a spray arm or shield a dirty surface, and you can spot both while the load is still in place.
| What you see | Where to look next |
|---|---|
| Food remains on the upper rack only | Check dish placement, spray-arm movement and holes, then any rear rack water-feed connection and the filter. |
| Both racks come out dirty | Check the filter, water supply, detergent and cycle. |
| Detergent residue remains on dishes | Check whether the load blocked the spray, then check the detergent amount. |
| Black or gray marks appear | Separate aluminum items from other dishes and give the load more space. |
Check the upper rack in order
Keep the load in place for the first two checks. After you correct something, run a comparable load. If the upper-rack dishes are still dirty, move to the next check.
- Look at the dirty side of each item. Face soiled surfaces down and inward toward the spray arms, and separate stacked or crowded dishes. If a dirty surface faces another dish, give it a clear path for the spray. Then check arm movement.
- Turn each accessible spray arm by hand with the dishes still loaded. It should make a full revolution without hitting anything. Move an item that catches it and turn the arm again. Once it can travel freely, inspect the spray openings.
- Look for blocked holes, visible damage and a loose upper-arm mount. Clear accessible debris using the cleaning method for your model. If an arm is damaged, arrange service. If the openings are clear and the arm is secure but the upper rack still comes out dirty, check the rack's water feed.
- If your model has a water-feed connection behind the upper rack, look at both parts as you close the rack fully. If they meet, check the filter next. If they miss, use your model's rack installation directions to reseat the rack and check the connection again. On a height-adjustable rack, make this check at the height you use. If the parts still do not meet, contact an appliance technician.
The last two checks point to different places. Debris visible in a spray hole calls for cleaning that opening. Clear holes with a rear feed that misses its connection point you to the rack connection; a clean, connected arm leads you to the filter check.
Clear blocked spray openings
An arm can turn freely while debris blocks its spray holes. Look over the openings and use your model's directions for removing and refitting the arm or nozzle.
On Bosch models, rinse the spray arms (opens in a new tab) and loosen debris in a blocked hole with a toothpick. Check that each cleaned opening is clear and that the arm is secure when you put it back.
If you find debris in the holes, clear it before judging the rack connection. If the holes are already clear, the arm turns freely and food remains only up top after a comparable wash, move to the rear-feed check in the numbered steps. That check is only for a rack with a visible connection behind it.
Check the filter even if only the upper rack is dirty
Food or debris caught in the filter can leave dishes less than clean. Filter removal varies by model, so use your dishwasher's directions before taking it out. If those directions allow it, soak the removed filter in warm, soapy water and gently brush off stubborn bits with a soft-bristled brush. Put every part back as your model directs and check that it locks before running a wash. If a filter is missing, damaged or loose, keep the dishwasher off. Our guide to cleaning a dishwasher filter covers the job in more detail.
Check the filter for trapped food as you clean it. Once it is clean and locked in place, a comparable wash tells you whether the loading, spray and filter checks have helped. If both racks still come out dirty, turn to the water, detergent and cycle checks below.
Check the wash conditions shared by both racks
If dishes on both racks are still dirty, make sure the water supply is on and run hot water at the closest sink for at least 30 seconds before a wash. Check that the cycle suits the dishes and that you used the right amount of detergent. Too much detergent can leave residue.
If the complaint is cloudy glassware rather than food left behind, our guide to cleaning cloudy glasses takes you through that problem.
If the dishes have dark marks
Black or gray marks can mean dishes sat too close together. Keep aluminum utensils and other aluminum items from rubbing against glasses and other dishes during the wash. If food is also left behind, return to the loading and spray checks.
If the upper rack stays dirty
If the arm is damaged, or the upper rack remains dirty after you check its spray path, any water connection and the filter, contact an appliance technician. Tell them which rack is affected and what you saw at each check.
Check your warranty before booking, and have your model and serial number and purchase receipt ready. The receipt helps establish the purchase date and warranty period. Ask for a repair estimate that includes the diagnostic fee, parts and installation. Compare that total with a replacement quote and any warranty coverage before authorizing work.
You can check your warranty paperwork (opens in a new tab) while gathering those details.
Two more questions before the next wash
Should I rinse the dishes first?
Scrape off food. On some newer dishwashers, a thorough pre-rinse can affect the soil sensor and lead to a shorter or less effective cycle. Follow your model's loading directions.
What if detergent stays in the dispenser?
On a Samsung dishwasher, empty the dishwasher, add detergent, and run a cycle. If the cycle completes without dispensing it, request service.
Can the arm turn and still leave the upper rack dirty?
Yes. Check its spray holes for debris. If they are clear and your rack has a rear water feed, check that the feed meets its connection when the rack closes. Then check the filter.
What if the dishes look cloudy instead of having food stuck on them?
Check the detergent amount and rinse aid. Too much detergent can leave residue, and a lack of rinse aid can leave dishes and glasses streaky or cloudy.
After any loading or cleaning change, wash a comparable load and check the same upper-rack spots for leftover food. That result tells you whether to continue through the checks or report a persistent upper-rack problem for service.
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