Find answers to common dishwasher questions here

I can see a red warning light

A warning light just means you need to top up the rinse aid or special salt. If you live in a hard water area, keep these topped up even if you’re using multi-benefit tablets like Finish Quantum.

There’s a rattling or knocking noise during the cycle

If dishes are touching each other, they can make a noise while the machine’s working. To stop this happening, load the dishwasher the right way: look at the dishwasher manual to find out how, or here.

The dosing chamber won’t shut

If you’re using powdered detergent, you might have overfilled the chamber. Or the mechanism could be blocked by spilled or dried-on detergent. You can prevent these problems in the future by switching to tablets.  

If cleaning the dishwasher chamber and using tablets doesn’t work, maybe there’s something wrong with the chamber’s closing mechanism. You’ll need to get an engineer to take a look. 

The dishwasher won’t start

The first thing to do is make sure the door’s shut properly. The dishwasher won’t work otherwise. Other quick dishwasher fixes are to make sure the machine's plugged in and switched on, and that the tap on the inlet pipe is open.

If these aren’t causing the problem, maybe the filter on the water-supply hose is blocked – perhaps by limescale. You’ll need to look at the dishwasher manual to find out how to clean it.

Finally, the thermal fuse might have tripped. If that’s happened, it has to be replaced. Again, you’ll need to look at the dishwasher manual to find out what to do. Or call the manufacturer’s technical helpline. 

The water’s not draining from the machine

The most likely cause is a blocked filter. Take it out and scrub it under the tap. To keep your dishwasher working well, clean this filter once a week, and use a dishwasher cleaner once a month. Scraping plates well before putting them in the dishwasher also helps. 

If the problem’s not a blocked filter, maybe the kitchen sink drain is clogged or the dishwasher’s drain hose is kinked. If you can’t easily fix these problems yourself, you might need to call a plumber. 

There’s a rattling or knocking noise during the cycle

If dishes are touching each other, they can make a noise while the machine’s working. To stop this happening, load the dishwasher the right way: look at the dishwasher manual to find out how, or here.

The dishes are still wet when the cycle’s ended

It could be because someone’s stacked the dishwasher so the water can’t circulate and run off easily. If you’re not sure of the best way to stack it, have a look here, or at your dishwasher manual. 

If you’re in a hard water area, make sure you add rinse aid, even if you’re using tablets that have rinse aid in them already. Rinse aid helps things dry properly.

If none if this works, there could be something wrong with the heating element in your dishwasher. Get an engineer to take a look. 

The detergent hasn’t completely dissolved

Make sure the detergent compartment can open properly. If it’s blocked by a big pot or plate during the cycle it might only open partway. Then only some, not all of the detergent can dissolve.  

Check the detergent compartment’s dry, too, before putting the detergent in it. Damp can make tablets and powder stick.

Can I put this in my dishwasher?

Stainless steel
Yes. Try to use high-quality stainless steel (18/8 and 18/10 are the best). Some cheaper cutlery, often labelled ‘rust-free’, might develop rust spots.

Aluminium
If you often put aluminium in a dishwasher, it can eventually discolour. This shows up as brighter areas on the bottom of pans, or black marks, for example on a garlic press.

Silver
Yes, but you need to avoid it getting tarnished. Wash off food containing sulphur first (for example, egg, mayonnaise or mustard), and make sure the silver isn’t touching anything made of stainless steel once it’s inside the dishwasher. Use a detergent like Finish with an integrated silver protection agent.

Plastic
Yes, if it’s marked ‘dishwasher-proof’. It might warp if it doesn’t have this label. Stick to low temperatures (50°C) too.

Wood
No. It can crack or swell. Also, some wooden parts – like knife handles – are glued, and the dishwasher’s heat might make the glue dissolve. 

Porcelain
Generally, yes. But ‘on-glaze’ patterns will fade in a dishwasher. You can tell if your porcelain has this sort of pattern, as it’s slightly raised, and you can feel it with your fingers. 

Why do my glasses look dull or cloudy?

It could be limescale if you live in a hard water area.

The cloudy look can also be caused by corrosion.

How can I get limescale off glasses?

Put them in a solution of white vinegar or citric acid. Or put them in the dishwasher and run a cycle with Finish Cleaner Machine. 

To prevent limescale deposits when you’re in a hard water area, you need to use dishwasher salt and rinse aid – even if you’re using multi-benefit tablets. Some dishwashers let you adjust the amount of rinse aid you’re using in each wash, so set yours to the maximum if you can.

How can I stop spots and smears appearing on my glasses?

The dishwasher needs to be stacked properly, so the water can circulate and run off easily.

Limescale can cause smears: get rid of them by following this advice.

Using too much rinse aid can cause streaks. Some dishwashers let you adjust the amount of rinse aid used in each wash have a look at the dial next to the dispenser. Too much detergent can cause the same problem. If you’re using powdered detergent, make sure you’re using the right amount. 

Can I get corrosion marks off glasses?

Once you’ve got corrosion on glasses, you can’t get rid of it, but you can help stop it forming in the first place. Use a low-temperature or glass cycle, and tablets that have built-in corrosion protection, like Finish Quantum. You can add Finish Protector, too.

My dishwasher’s not cleaning very well

There are quite a few reasons this can happen, and the effects vary: sometimes the only sign is a little tea or coffee left in cups. The main things you can do to help are:

  • If you live in a  hard water area, make sure you’re using enough powder or gel detergent. And that you’re using dishwasher salt, which you’ll need even with multi-benefit tabs.
  • Load your dishwasher the right way, and don’t put too many things in it. It means water can circulate properly during a wash.
  • Scrape the plates before you put them in and wipe sauce and gravy off with paper towel.
  • Clean the filter under the tap if it’s looking clogged. And use a dishwasher cleaner like Finish Cleaner Machine regularly.
  • Make sure nothing’s blocking any moving parts, like the spray arms or the detergent dispenser.
  • Use a standard program like eco or auto for the dirtiest dishes rather than a quick program. 

We’ve got more suggestions of what to do if the spray arms might be clogged or the detergent hasn’t completely dissolved

Why do plastics sometimes get stained?

Plastics get porous over time, so strongly coloured foods (like bolognese, curry or anything with tomatoes in) can temporarily dye them. Scraping plates well and wiping sauce off with paper towels before putting them in the dishwasher will help. The stains will fade if you put the plastic in strong sunlight. 

My plastic dishes smell of perfume

This is probably because you’re using a dishwasher freshener. Because plastic is porous, it can absorb smells, but they’re not harmful. Washing the plastics again without using a freshener will get rid of the smell.