The ticket reads: “The dishwasher doesn’t take in water or drain, and it won’t go into diagnostic mode. Another company replaced the control board, but it still didn’t work.”
By the time a homeowner in Nepean called TechVill, they had already paid for one repair on their Bosch dishwasher. The diagnosis they had been given — a failed control board — sounded reasonable. The new board went in, and the dishwasher stayed exactly as dead as before.
What the customer reported
No water intake, no draining, no response to the service-mode button sequence. The unit is a Bosch SHXM78Z55N/22, a current-generation built-in model.
What the diagnostic showed
TechVill technician Alpeshkumar did not start from the previous company’s conclusion. He started from the symptom and tested the unit again: no water was reaching the tub at all, and the machine was not turning on.
That second observation matters more than it first appears. A dishwasher that will not enter diagnostic mode is not necessarily a dishwasher with a bad board — it can be a dishwasher that is not receiving clean power to begin with. A control board cannot run a fill or a self-test on a supply it is not getting. Working through the problem with Bosch technical support, Alpeshkumar went upstream of the electronics to the junction box where the household supply connects to the appliance.
The wiring inside had burned. The photo shows melted insulation and scorching at the terminal block — a connection that had been overheating long enough to destroy itself. That was why the dishwasher would not power up properly, and it is why a new control board changed nothing: the board was never the part being starved.
What we did
Alpeshkumar remade the supply connection properly and replaced the water inlet valve, since the unit had not been taking in water. Then he ran the dishwasher through its test — fill, wash and drain all working normally.
Components replaced:
- Water inlet valve (genuine Bosch service part) – the solenoid valve that opens on the control board’s command to let water into the tub, and closes to stop the fill
The repair was quoted at $458.50 before 13% HST, with half paid upfront on the first visit. It carries TechVill’s 90-day labour warranty.
Why the job was not finished when the dishwasher worked
Burned wiring does not happen for no reason. A loose terminal, an undersized conductor or a failing connection upstream will overheat again, and reconnecting the wires fixes the dishwasher without fixing that. So the dishwasher was left working, and the homeowner was left with a clear recommendation: have a licensed electrician find out why the junction box burned and replace it. The household wiring is outside an appliance technician’s scope, and the honest thing is to say so rather than close the ticket.
Why the difference matters
Two repairs were done on this dishwasher. The first replaced an expensive part on the most plausible guess. The second tested whether the machine was being powered before blaming the component that runs it. When a replacement part changes nothing, that is diagnostic information: the fault was never in that part, and the next step is to go back to first principles rather than order the next most likely component.
TechVill is factory-authorized by Bosch, and that relationship includes direct access to Bosch technical support on cases like this one. Book online to schedule a Bosch dishwasher diagnostic with our team.
