More than any other brand, Bosch generates calls that are not faults. The machines are well built and they last, and two of their design decisions are so unlike an American dishwasher that owners reasonably conclude something is broken.
Let us clear those two up first, then get to the real faults.
"It leaves plastics wet"
Most Bosch dishwashers do not have an exposed heating element in the tub floor. They dry by condensation: the final rinse is hot, the stainless tub is cooler than the load, moisture migrates to the tub wall and runs down the drain. It is quieter, gentler on plastics, and uses less energy.
It also does not evaporate water off plastic. Plastic has low thermal mass — it cools instantly and never gets hot enough to shed its water — so tumblers and container lids come out beaded while the glass and crockery come out dry.
This is the design, not a defect. What genuinely helps:
- Use rinse aid, and do not let it run out. On a condensation machine rinse aid is not optional; it is the whole mechanism for making water sheet off rather than bead. Half the "not drying" calls are an empty rinse-aid reservoir. Check the indicator.
- Turn the rinse-aid dosage up if you have soft water, which most of Greater Boston does on MWRA supply.
- Crack the door at the end of the cycle. Many models do this themselves.
- Load plastics on the top rack, and accept that they are the last things to dry.
"The bottom is always wet inside"
A small amount of standing water in the sump is normal and intentional — it keeps the seals from drying out. A tub with visible standing water above the filter is not.
Now the real faults
E15 and the base tray float. Bosch machines have a leak-protection system with a float in the base tray. If water collects there, the float rises, the machine goes into protection, refuses to run, and often runs its drain pump continuously. E15, or a machine that just hums and will not start.
Tilting the machine back to drain the tray clears it and the machine runs again — which is why so many forums tell you to do that. But the tray filled for a reason. Something above it is leaking: a hose clamp, the sump gasket, the door seal, or a heat-exchanger connection. If yours has been tilted more than once, stop tilting it and find the leak.
Drainage. Same universal checklist as any machine: the filter assembly in the tub floor (unscrew, rinse, refit — quarterly), the drain hose high loop or air gap, and whether the disposer knockout plug was removed at install. Bosch's fine filter clogs quietly and produces gradually worse cleaning long before it produces an error.
The wash arms. Spray holes silt up with label paper, seeds and grit. Pull the arms — they usually unclip or unscrew by hand — and check every hole is open.
The internal water softener. European-market Bosch machines, and many sold here, have a salt reservoir in the tub floor with its own hardness setting. On MWRA water — which is very soft — set that to its lowest value. Over-softening already-soft water contributes to glassware etching, which is permanent. North of Lynn, where much of Essex County is on genuinely hard local supply, do the opposite: fill the salt and set the hardness to match your town's published number.
Door hinge cables and springs. Bosch doors are counterbalanced on cables over pulleys. When a cable frays and snaps the door drops like a trapdoor. It is a known wear item, it is a reasonable repair, and a door that has started slamming is telling you the cable is on its way.
Repair economics
Bosch is one of the brands where repairing an older machine usually makes sense. Parts availability is good, the tubs are stainless rather than plastic, and the mechanical design is serviceable. Pumps, filters, hoses, hinge cables, door seals, wash arms, heaters and control boards are all replaceable, and the machine that receives them typically has years left.
Where we will tell you to stop is a corroded or cracked stainless tub, and a control failure on a very old unit where the board is no longer produced.
Before you call
Note the E-code if there is one, check the rinse-aid indicator, and pull the filter out and look at it. If your complaint is "it does not dry my plastics," read the first section again and save yourself the diagnostic fee — that one is genuinely free advice.
