I have a Bosch dishwasher (model SHX46A05UC/43) that occasionally fails to get all the soap scum off of the dishes. It seems like it fails to fully finish cleaning once every five to ten cycles.

I feel like it might be something to do with the heater. The cycles the dishes do get fully clean, the dishes are almost too hot to touch at cycle end, while following cycles where the dishes are not fully clean, the dishes are only warm.

The heater is capable of working, as during testing I observed water temperatures around 150°F mid-cycle.

Things I have confirmed:

  1. Pump: Opening the dishwasher while it's running shows the arms spinning and spraying. Water fully is removed from basin after the cycle is finished
  2. Arms: I have removed and cleaned the arms and they don't seem to be clogged.
  3. Traps and drains: appear to be cleaned are not gunked up.

Can anyone suggest what might be wrong? The inconsistency in the issue is making it hard to track down.

  • I have a similar problem. Did you find a solution?
    – Vingtoft
    Feb 1, 2018 at 9:19
  • @Vingtoft Not as of yet. It seems to be a control board issue. I've taken to setting a timer to 45 minutes when I start the cycle. When the timer goes off, I see if the water is very hot (~150°F), and if it's not I cancel the cycle, switch the mode to Power Scrub Plus (or back to normal), and start again. I suspect the issue is a bad control signal and/or relay.
    – John
    Feb 6, 2018 at 2:07
  • @Vingtoft See my solution below, and if you're still having an issue, examine the heater relay on the control board. It is a common issue with this line of dishwasher and one I have fixed before. The intermittent nature of this issue caused me to not look closely here before, but given the history of this model, I should have looked here sooner. I hope yours is working, but if not, take a look.
    – John
    Apr 12, 2018 at 16:41

1 Answer 1


After a few months of rerunning failed washes, I found the issue... I hope.

I disassembled the dishwasher's front and removed the control board. Upon close inspection there were two dead/fried ants (yes, the insect) on the bottom of the control board near the pins for the relay the heater. This relay is already unreliable in this dishwasher model and I have fixed it before.

One of the solder joints connecting the relay looked like a cold solder joint. Cold solder joints can sometimes have intermittent connection issues so I was hopeful that this was the issue. I suspect the ants were in there during a run and caused the pins to arc which melted the solder joints.

I removed the solder from the joints and re-soldered the pins. I reassembled the dishwasher and have had two successful runs so far. Fingers crossed this resolves the issue. 🤞🤞🤞

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