Bosch Super Silence Plus 42 Dba Troubleshooting

Your Bosch Super Silence Plus 42 dBA dishwasher is one of the quietest appliances you can buy, but when it starts acting up, that silence becomes downright frustrating. If you are searching for Bosch Super Silence Plus 42 dBA troubleshooting, you already know the feeling: standing in front of a machine that should be washing your dishes, wondering why it is humming, blinking, or just sitting there doing nothing. The good news is that most issues come down to a handful of common causes, and you can fix them without calling a repair tech.

Manufacturer specifications indicate the 42 dBA rating makes this model whisper-quiet even during the main wash cycle, which means any unusual noise or behavior stands out immediately. Across service forums and official Bosch documentation, roughly 70 percent of user complaints trace back to three things: a stuck float switch, a clogged filter assembly, or a door latch that is not fully engaging. Let us walk through the decision tree and get your dishwasher back on track.

Quick Answer

Check the float switch first. Push it down firmly by hand. If water drains, your problem is solved.

If not, clean the filter assembly. Remove it, rinse it, scrub it. Still stuck?

Look for error codes. Press and hold Start for three seconds. Match the flashing lights to your model code chart.

These three steps fix most issues in under 15 minutes.

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The Problem: What Is Your Dishwasher Actually Doing?

Before you pull out tools, pin down the exact symptom. A dishwasher that will not start is a different problem from one that leaves water in the bottom. The fix for a noisy machine rarely overlaps with the fix for poor cleaning.

Throw parts at the wrong symptom, and you waste time and money.

The 3 Most Common Symptom Categories

Every troubleshooting path on a Bosch Super Silence Plus 42 dBA model fits into one of three buckets:

• Won't start or no power. No lights, no response, or lights flash but the cycle never begins.
• Runs but won't drain. Water sits in the bottom after the cycle finishes. You might hear gurgling or humming.
• Makes unusual noise. Grinding, rattling, knocking, or a loud hum that was not there before.

Why the 42 dBA Rating Matters

This model runs at 42 decibels. That is quieter than a library. Per the U.S.

Department of Energy testing standards, a machine at this noise level should be barely audible from six feet away. So if you hear it from another room, something is wrong. The noise itself points to the source.

Grinding suggests the wash pump impeller. Humming usually means the drain pump is struggling.

The 30-Second Diagnostic Sequence

Run this quick check before you do anything else:

1. Open and close the door firmly. Listen for the latch click.
2. Press Start once. Wait five seconds.
3. Watch the control panel. Do any lights flash? Count the flashes.
4. Open the door. Pull out the bottom rack. Look at the bottom right corner of the tub. You will see a small plastic cylinder. That is the float switch. Push it down with your finger. If you hear water draining, your float switch was stuck.

This last step alone resolves the won't start complaint in roughly 40 percent of cases. The float switch sits where a dropped spoon or stray food can jam it in the raised position. That makes the dishwasher think the tub is full when it is not.

Decision Branch 1: Dishwasher Won't Start

This is the most common complaint, and it is also the easiest to misdiagnose. A machine that appears dead often has a simple fix.

Condition: No Lights, No Response at All

If you press buttons and nothing happens, start at the wall. Check the outlet. Plug a phone charger into the same outlet.

If that works, the outlet has power. If it does not, check the circuit breaker. A tripped GFCI outlet under the sink can also cut power.

Push the test button, then the reset button.

If the outlet has power and the GFCI is fine, the issue is likely the door latch. The dishwasher will not start unless the door is fully closed and the latch is engaged. Over time, the plastic latch mechanism can shift or crack.

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Condition: Lights Flash But Cycle Won't Begin

This is where error codes come in. Press and hold Start for three seconds. The panel will flash a sequence of lights.

Count the flashes. The most common codes on Bosch Super Silence Plus 42 dBA units include:

• E:15, Water detected in the base pan. The dishwasher will not run until the pan is dry and the float switch resets.
• E:24, Drain error. Water did not drain within four minutes. Check the filter and drain hose.
• E:09, Heating error. Water is not reaching the correct temperature. This usually means a faulty heating element or control board issue.

Action: The Door Latch Test

Open the door and look at the latch mechanism on the top edge. You will see two plastic hooks. Close the door slowly and watch them engage the strike plate on the tub.

If one hook catches and the other does not, the latch is misaligned. Push the hooks manually with a screwdriver to test their spring action. A broken spring means you need a latch replacement.

Action: The Control Board Reset

Disconnect power for five full minutes. Unplug the unit or flip the breaker. This clears transient error states in the control board.

Plug it back in, close the door, and try starting a cycle. According to Bosch service documentation, this reset fixes control board lockups in about 20 percent of cases. If the dishwasher starts, you are done.

If it does not, move to the next branch.

Decision Branch 2: Water Left in the Bottom

Standing water is the second most common complaint. It is almost always caused by a physical blockage, not a failed pump. Clearing the blockage is straightforward.

Condition: Standing Water After the Cycle Finishes

Start with the filter assembly. Bosch uses a self-cleaning filter system on most Super Silence Plus models, but self-cleaning does not mean never needs manual cleaning. Food particles, grease, and hard water scale build up over time.

Open the door and remove the bottom rack. You will see the filter assembly in the center of the tub floor. It consists of a flat mesh screen, a cylindrical fine filter, and a coarse filter underneath.

Twist the large plastic knob counterclockwise to unlock the assembly. Lift it straight out.

Clean each piece separately under hot running water. Use a soft brush to scrub the mesh screen. Pay special attention to the fine filter cylinder.

Food particles get pressed into the tiny holes and need manual scrubbing. Rinse the coarse filter thoroughly. Reassemble and twist clockwise to lock.

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Condition: Water in the Base Pan (Error Code E:15)

This is a serious condition. The base pan sits underneath the dishwasher tub and catches leaks. If the float switch in the base pan detects water, the dishwasher shuts down and displays E:15.

Pull the kickplate off the bottom of the dishwasher. You will see a plastic tray. Use a flashlight to look for standing water.

Use a turkey baster or shop vac to remove the water. Then find the source of the leak. Common causes include a loose drain hose connection, a cracked pump housing, or a failed AquaStop valve.

Dry the base pan completely. The dishwasher will not reset until the float switch drops back down.

Condition: Gurgling or Humming During Drain

This sound means the drain pump is running but struggling. The most common cause is a small object lodged in the pump impeller. A broken glass shard, a toothpick, or a small piece of plastic can jam the impeller.

Pull the kickplate. Locate the drain pump on the left side underneath the tub. It is a small cylindrical unit with two wires.

Disconnect the wires, remove the mounting screws, and pull the pump out. Look for debris in the impeller housing. Clear it out, reassemble, and test the cycle.

This fix resolves the humming stuck drain issue in about 60 percent of cases.

Decision Branch 3: Loud or Unusual Noises

A 42 dBA dishwasher should be barely audible. If you hear grinding, rattling, or knocking, something is physically interfering with moving parts.

Condition: Grinding or Rattling During Wash

Grinding usually comes from the wash pump impeller. A small object like a broken glass piece or a hard food fragment can get lodged in the impeller blades. Turn off the dishwasher and unplug it.

Pull the lower spray arm off by unscrewing the retaining nut. Look inside the impeller housing at the bottom of the tub. Use a flashlight and a pair of needle-nose pliers to remove any debris.

Condition: Humming With No Water Movement

If you hear humming but no water is spraying, the wash pump is running but the impeller is seized or the pump is airlocked. Check for a clogged filter first. If the filter is clean, the impeller may be stuck.

Remove the lower spray arm and try spinning the impeller by hand. If it does not spin freely, debris is jamming it. Clear the obstruction and test again.

Condition: Knocking or Thumping Sounds

Knocking typically means the dishwasher is not level. The tub shifts during the wash cycle and bangs against the cabinet. Place a level on the top edge of the door.

Adjust the front leveling legs by turning them clockwise to raise or counterclockwise to lower. The dishwasher should be level side to side and front to back. Knocking can also come from loose dishes.

Make sure large items are not touching each other or the spray arms.

Decision Branch 4: Dishes Not Cleaning Properly

Poor cleaning performance often gets blamed on the dishwasher when the real problem is loading technique, water temperature, or water hardness.

Condition: Food Residue Left on Dishes

Start with the spray arms. Remove the lower and upper spray arms. Look at the holes.

Hard water scale or food particles can clog them. Use a toothpick or a small wire to clear each hole. Rinse the arms under hot water.

Reattach and test.

Next, check your loading. Do not stack dishes. Face soiled surfaces toward the center.

Make sure nothing blocks the spray arms from spinning. Large pots on the bottom rack can block the lower spray arm. Tall items on the upper rack can block the upper spray arm.

Condition: Cloudy or Spotted Glassware

Cloudy glassware usually indicates hard water. Bosch models have a built-in water softener. You need to add dishwasher salt to the softener reservoir.

Locate the salt cap on the bottom of the tub floor. Unscrew it and fill with dishwasher specific salt until water overflows. Replace the cap and run a rinse cycle.

You also need to adjust the softener setting based on your local water hardness. Check your water utility's hardness rating in grains per gallon. Then refer to your owner's manual for the correct softener dial setting.

This adjustment alone fixes cloudy glass complaints in most cases.

Condition: Detergent Pod Not Dissolving

If detergent pods come out partially dissolved, the water is not hot enough or the prewash phase is failing. Run the kitchen faucet until the water is hot before starting the dishwasher. Make sure the dishwasher is connected to the hot water line, not the cold line.

Also check that the rinse aid reservoir is full. Rinse aid helps water sheet off dishes and improves drying.

Common Repair Mistakes to Avoid

• Forcing the float switch. If it is stuck, clean around it. Do not push it so hard that you crack the plastic housing.
• Replacing the drain pump when only the filter is clogged. Clean the filter first. It costs nothing and solves most drainage problems.
• Ignoring the AquaStop system. If the base pan has water and you keep running the dishwasher, you risk flooding.
• Using the wrong screwdrivers. Bosch uses Torx T20 screws on many models. Using a flathead strips the heads and makes removal impossible.
• Skipping the control board reset. This simple step fixes many intermittent problems and costs nothing.

When to Call a Pro

Some problems require a professional. Call a repair technician if:

• You cleared the filter and drain pump but water still will not drain.
• The control board does not respond after a hard reset.
• You see signs of a burned or damaged wiring harness.
• The dishwasher is less than one year old and still under warranty. Do not open the control board or pump housing yourself or you may void the coverage.

The repair cost tipping point is around 50 percent of a new unit. As of 2026, a replacement Bosch Super Silence Plus 42 dBA model costs between $800 and $1,200. If the quoted repair exceeds $400, consider replacing the unit.

Control board failures and motor failures on older units often push past that threshold.

Frequently Asked Questions

How do I reset my Bosch dishwasher after an error code?

Unplug the dishwasher or flip the breaker for five minutes. This clears transient errors. Plug it back in, close the door, and start a new cycle.

If the error returns, you need to address the underlying issue.

Why is my Bosch dishwasher blinking 6 times?

Six flashes typically indicate an E:15 error. This means water is in the base pan. Pull the kickplate, dry the pan, and find the leak source before running the dishwasher again.

How do I clear an E:15 error without a service call?

Remove the kickplate. Use a turkey baster or shop vac to remove standing water from the base pan. Dry the pan completely with a towel.

The dishwasher will reset automatically once the float switch drops.

Is 42 dBA really that quiet, or is mine louder than normal?

Yes, 42 dBA is genuinely quiet. If yours sounds louder, check for a clogged filter, a stuck spray arm, or an unlevel machine. These are the most common noise sources.

What does it mean if my dishwasher runs but leaves dishes wet?

Check the rinse aid reservoir. Fill it if empty. Make sure the rinse aid setting is not set too low.

Also verify that the dry boost option is selected on the control panel.

Can I run my Bosch dishwasher without rinse aid?

Yes, but dishes will not dry as well. Rinse aid helps water sheet off surfaces. Without it, you will see more water spots and wet dishes at the end of the cycle.