Is your Bosch dishwasher not draining anymore? Don’t fret! This is a prevalent complaint among Bosch dishwasher users, affecting thousands of households annually. Fortunately, troubleshooting is not as tricky as it may seem.
The first step in clearing this issue is checking for the presence of a blockage, although it is not the only cause.
In some cases, a Bosch dishwasher won’t drain but there is no blockage.
Blockage or not, in this troubleshooting guide, you will find the best solutions to this frustrating problem. Additionally, we’ll explore all the possible causes behind it.
Why is Bosch Dishwasher Not Draining Water?
Experiencing a sudden draining failure will leave you with piles of dirty dishes and smelly standing water in the dishwasher. This issue may occur due to a clogged filter, blocked drain line, a faulty drain pump, and many other reasons. If your Bosch dishwasher is not draining at the end of the cycle, you should consider the following culprits:
Related Article: Bosch Dishwasher Problems
Blocked filtering system
In a Bosch dishwasher, this system relies on an advanced mesh filter. It catches stuck food chunks and prevents them from reaching the clean dishes or obstructing the pump. With frequent use, the filter can get filled up with food residues hindering its functionality.
Twisted hose
When a Bosch dishwasher is not draining and has no blockage, you should take a look at the drain hose. This hose removes the water from the dishwasher to the drainpipe. This hose should remain straight to perform its function. Therefore, a bent hose will make the dishwasher not drain.
Failed drain valves
Drain valves play a critical role in single-motor Bosch dishwashers. Each appliance is equipped with a drain valve, which is also known as a check valve. This valve consists of two main components: a solenoid, and a gate arm with two springs.
At the end of each wash cycle, the valve opens smoothly allowing wastewater to drain. A failed valve won’t open, causing stale water will build up.
Blocked air gap
Although not all Bosch dishwasher models are equipped with an air gap, many of them come with it. Primarily, this gap acts as a protective shield or a barrier preventing wastewater from mixing with the clean water supply.
If your Bosch dishwasher has a looped drain hose, installing an air gap won’t be essential. However, in some cities, it is obligatory to have an air gap to have this device.
An air gap is mounted on the countertop next to the sink. It gets blocked by any small object or large food chunks.
Jammed garbage disposal
Garbage disposal is a main plumping device that prevents clog formation in the drain. It grinds or chops food particles before allowing them to access the drain. Over time, this disposer will get blocked by food chunks.
Faulty drain pump
As the name suggests, a drain pump is a device that pumps wastewater down the drainpipe. The pump relies on its motor to function properly. However, this part might get defective over time. A damaged pump may be associated with various factors such as:
- Age
- Frequent overloading,
- Stuck objects
- Water buildup
Defective wash impeller
A wash impeller of all Bosch dishwashers is the same as the spray arm of other brands. It is a small blade that rotates to spray water all over the dishes. A damaged or worn-out wash impeller is a primary cause of the Bosch dishwasher not draining issue despite no blockage. Additionally, its small spray holes might become closed by food deposits.
Problematic drain impeller
A drain impeller is similar in shape to a wash impeller. Additionally, both are located at the bottom of the appliance. However, they vary in role and function. As the name suggests, this impeller facilitates the removal of wastewater all the way to the drain. The impeller runs at the end of each wash cycle.
Malfunctioning solenoid
Any valve in a Bosch dishwasher contains a solenoid kit. This small electromagnetic component relies on the open-shut mechanism depending on the phase of a wash cycle. At the start of each cycle, the valve automatically opens allowing water to flow smoothly to the dishwasher. Once the washer is filled, it shuts off.
At the end of the cycle, the valve opens once again allowing stale water to leave to the drain. So, when this kit malfunctions, the water flow would be either insufficient or too excessive. Additionally, it contributes to the Bosch dishwasher not draining problem.
Dead control board
If your Bosch dishwasher is not draining but no blockage is detected, it might be a problem with the control board. This device controls all the functions of any dishwasher by giving orders to the relevant parts. Therefore, any sort of failure in this panel might cause draining failure and other complicated issues.
How to fix Bosch Dishwasher not draining?
To properly address the issue of Bosch dishwasher draining failure, it is crucial to diagnose the underlying cause. Depending on the diagnosis, you can take the correct action including removing, replacing, or readjusting the problematic parts.
Before attempting any repairs or maintenance unplug the dishwasher, shut off the water supply, and empty any standing water from the bottom of the dishwasher.
1. Clean the filter
The filter of a Bosch dishwasher is located behind the bottom rack. It can be easily removed and reinstalled. To correctly clean the filter, use running water and a soft brush. Rinsing its covering is beneficial too.
2. Straighten out the hose
A bent drain hose won’t let the wastewater flow smoothly. Therefore, you need to inspect it for kinks. If they are minor, you can easily straighten them. If this is not possible, you should consider a new drain hose.
3. Unclog the drain valve
A functional valve allows water to drain out without reversing back to the dishwasher tank. However, it might get obstructed by broken glass plastic pieces or even food particles. In other cases, this valve might become defective or damaged.
In the case of clogging, you can try cleaning it with vinegar and baking soda mix. However, a damaged valve needs replacement immediately.
4. Clean the air gap
One of the telltale signs indicating a blocked air gap is water leaking from its opening. Additionally, standing water in a Bosch dishwasher tub may occur due to a plugged gap. Inspecting the gap and clearing any obstructions should resolve this issue.
5. Unclog the disposer
Before assuming that the garbage disposer is the cause of your Bosch dishwasher draining failure, you can perform a simple test. Turn both the disposer and the dishwasher on and run water through them. If it makes an unusual noise, it indicates blockage. This calls for immediate cleaning with hot water to loosen any stubborn debris.
6. Replace the pump assembly
Unfortunately, there are fixes to restore a damaged drain pump. If the motor is defective, you will need a new pump assembly to fix a Bosch dishwasher that won’t drain.
7. Get a new wash impeller
You can identify a faulty wash impeller through visual inspection. Look for cracks and signs of tear. Also, it might not rotate or make noise. If you notice any of these malfunction signs, it is recommended to opt for a replacement wash impeller for Bosch dishwashers.
A clogged impeller, on the other hand, is easy to clean by soaking it in baking soda and white vinegar solution. Afterward, scrub it with a brush under running water to restore its cleanliness.
8. Replace a damaged drain impeller
A defective drain impeller won’t rotate. Thus, wastewater accumulates and overflows. Depending on the cause of the malfunction, you can find the right fix. For instance, if it was only obstructed by food or other elements, clearing and cleaning it will fix the problem. However, a cracked or damaged impeller should be changed.
9. Replace the solenoid kit
In addition to inadequate water flow and draining failure in a Bosch dishwasher, you can identify a defective solenoid by its sound. A functional solenoid emits a recognizable clicking noise. In the case of a malfunctioning kit, you should get a new one.
10. Get a new control board
Fixing a dead control board is costly and not usually efficient. In fact, the cost of replacing an old board might not be very different from buying a new appliance. So, it is recommended to check and compare the cost of both options before making a decision.
Related: Bosch Dishwasher Parts
How to prevent Bosch Dishwasher not draining?
Despite the frustration of a Bosch dishwasher that won’t drain, prevention of drainage failure is possible. By following these steps you can minimize the chances of draining failure in a Bosch dishwasher:
Run a clean cycle
Once a month, run this empty cycle to ensure the removal of any stuck deposits. It is not required to add any sort of detergent or any dishes. Instead, pour one to two cups of white vinegar into the dishwasher’s bottom and start a normal cycle.
Perform a hot water cycle
Unlike a clean cycle, a hot water cycle requires loading the dishwasher and adding detergent. A hot cycle is more efficient in removing stuck particles and grease compared to a regular cold cycle. Repeat this cycle once or twice a week.
Remove food particles before washing
Before loading your Bosch dishwasher, it is advisable to remove food chunks to avoid clogging. You can remove them by hand if they are not stuck. For stuck particles, you can try soaking in warm or hot water for about 30 minutes.
Conclusion
Troubleshooting the Bosch dishwasher not draining issue is not difficult once you diagnose the cause. Some common reasons this could be happening is when there is a blockage in filters, valves, or impellers. Otherwise, broken or cracked components are to blame for the Bosch dishwasher not draining issue despite no blockage.
In either case, addressing the causes is easy and does not require many tools or complicated technical steps. Make sure to unclog the filters and valves, and all the removable components and clean them regularly. Also, replace damaged components showing signs of wear and tear.
However, if you find difficulty in troubleshooting your Bosch dishwasher, do not hesitate in contacting a professional technician.
Also, if you encounter other problems with your Bosch dishwasher, you can take a look at these articles:
Related Article: Bosch Dishwasher Owner’s Manual
Related Article: Bosch Dishwasher Leaking
Related Article: Bosch Refrigerator Problems
Adrian is an ISCET licensed professional that has completed the National Appliance Service Technician Certification Exam and has the expertise to diagnose and repair any appliance. He is well-versed in the latest technologies and techniques and is always up-to-date on the latest industry standards.
