Have a Bosch dishwasher. Been excellent. 15 years old.
Last few months, despite changing tablets, cleaning filters, using all the settings, a lot of food remains on plates, coffee grounds in mugs and stuff.

I thought they either worked or failed, but it seems just to have less washing power. Is that right, can it be revived easily, or should we look for another one?

Never owned one, but can the jets become blocked?

Take the spinning arms off and check the jets for blockages

Have you cleaned the spray arms, it’s surprising what works its way into the little holes. Do you use the same programme every time, if so try using the hottest one.

Do you use any eco settings or low temp settings? We replaced our dishwasher about 4 years ago and it had a eco setting which it defaulted to and after a few weeks of using that setting it started becoming less effective, started smelling and a layer of orange gunge started to form, so since then I’ve been overriding the eco setting and using it on the good old 65 degree wash and all is fine with the world. Just run it on the hottest stetting, they use tiny amounts of water so even on the hot setting they don’t use that much energy. At the 30 degree eco wash settings all you’re doing is creating the perfect environment for germs to thrive.

But yes, check the holes in the arms are clean and clear.

My Bosch will revert to this state every now and again. I find the rollers that the tray wheels sit in accumulate gunk. Take them all out, dismantle the lot, clean it all including in the arms and run it through a hot wash with a few scoops of soda crystals. Brings it back to as new working, it’s ten years old.

I wouldn’t say they get less efficient but things start to fail. As others said check the spray arms first. Might be worth checking the rubber seal that the top basket spray arm pipe goes into when the basket is pushed in (at the back of dishwasher about the size of a £2) as this can wear meaning no water goes into the upper spray arm so only the bottom one works and therefore wash half a load. An easy fix and only a couple of pounds to replace. Another thing may be the heater has gone so its only washing with cold water only, if this is the case i would just get a new dishwasher.

Mine does this, stick one of those finish dishwasher cleaner packs in it, run a cycle and it normally sorts it out

Is it draining properly? Ours (also a Bosch) wasn’t cleaning very well, until it eventually stopped working with an error code.

Turns out a coffee bean had somehow made its way past the filters and was caught in the two plastic ribs in the the outlet. Touching the pump impellers just enough to slow them down so the dirty water wasn’t draining properly during the wash cycle.

Easy enough to DIY, the front comes off to give you access to the pump etc.

Other thing to check is do you have anything that is stopping the upper washer arm from turning? Ikea plates are too big for our dishwasher – so we have to load it carefully.

Take the spinning arms off and check the jets for blockages

And the suction pump wheel under the filter.

Took mine apart the other week and was(not) surprised to find the arms were blocked with limescale and the suction pump to be covered in limescale too.

I used liberal application of that horrible limescale remover and elbow grease, left the arms to froth for a little while then poked a kebab stick (sharpened) into the holes and that cleared it all.

Then ran through those Calgon/dishwasher cleaning tablets a couple of time on Hot..

Works fine now.

Mines about 10yrs old BTW and only ever ran those cleaning tabs through it…

Have tried hot wash setting, was a bit better but not really 100% better.

Spray arms are best bet. In hand. @andy4d — I see the coupling you refer to, not sure there is a seal but will check manual to see if one should be there. Spray arms off now. Upper arm seems a bit loose on its fitting, but that might deliberate – or it might be why it doesn’t spray so well.

Cheers all!

They shouln’t degrade, but they can get clogged up with waste.

Take all the fittings out – spinning arms, the feed from the base to the top drawer, the filter. Scoop out whatever sludge is in the filter sump – watch for shards of broken glass. Usually somewhere in the sump will be an inspection window for the pump. Remove this & check the pump impeller isn’t fouled then close it up again.

Put a real nasty tablet in – finish powerball, aldi’s equivalent or a proper calgon cleaner & run it on its hottest setting with everything removed (yes including the filter). While it’s on clean teh filter then grab a vacuum cleaner and vacuum out the spinning arms. Try and jam spokes in the nozzles at the end of the arms to remove things like peas, sweetcorn or the random bit of lego I once found. Run them under the tap to make sure they flow freely. Put it all back together checking there’s nothing untoward in the sump.

My eyesight is going, so I probably miss a few specs of dried on food. I definitely attack the pans with less vigour than a few years ago. So I’m increasing worried my wife may be thinking of a replacement…

If you get any limescale then the water softener powered by the salt you put in the machine has probably failed .
A dishwasher should be almost spotless inside.

Limescale unlikely to be the issue for kcal. We never use salt either.

If you have soft water then you can usually get away without it , like I wrote if , but otherwise its the perfect way to degrade your machine , like others have pointed out is seems most likely a blockage or restriction.

Well – a bit obvious – thought he arm was swinging OK, but it was sometimes fouling on some of the plates. Not much, but enough.

Am now more familiar with taking all the bits apart now. Older d/w so no washer / seal that I could see.

rms now cleaned, d/w now purged, and cleaned generally, and have raised the upper tray to clear plates. Hopefully all now sorted. cheers all.

Make sure the strainer in the bottom is hole free and screwed down to stop the bits getting into the arms.