What Does Error Code E37 Mean on a Bosch Washing Machine?
Turn off the machine at the mains, wait 10 minutes, then turn the water supply tap fully off before restarting — if the inlet valve was temporarily stuck, this allows it to reset and the drum to drain to a safe level (takes about 5 minutes).
Fault description
Error code E37 is Bosch's overfill warning. It means the machine's control board has received a signal — or failed to receive the correct signal — indicating that water inside the drum has risen beyond the safe maximum level. The two systems most likely responsible are the pressure switch, which monitors water level, and the water inlet valve, which controls how much water enters the machine.
When E37 triggers, the machine will typically halt mid-cycle, and in many cases it will attempt to drain the excess water before locking out further operation. You may notice the drum sitting unusually full, or water visible through the door glass higher than normal. The machine will not continue the wash programme until the fault is resolved.
In most cases this is a fixable problem at home, but it does require methodical checking of a few components. Work through the steps below before calling a service technician.
Causes
- Faulty or blocked pressure switch — The pressure switch (also called a water level sensor) uses air pressure through a small hose to detect how full the drum is. If the switch itself has failed, or the hose connecting it to the drum is kinked, blocked, or split, it can send incorrect readings to the control board, triggering an overfill error even when water levels are normal.
- Water inlet valve stuck open — The inlet valve is an electrically operated solenoid valve that opens to let water in and closes when the correct level is reached. If the valve's solenoid fails or debris holds it partially open, water continues to enter the drum even after the control board has stopped sending the open signal, causing genuine overfilling.
- Blocked or kinked pressure switch hose — Even if the pressure switch itself is working correctly, a hose that has become clogged with detergent residue or has developed a kink will prevent accurate pressure readings from reaching the switch. This can cause the machine to misread the water level and trigger E37.
- Control board fault — In less common cases, the main PCB may be sending incorrect signals to the inlet valve, failing to close it at the right time, or misinterpreting the pressure switch data. This is usually only suspected after all other components have been checked and found to be in good condition.
- Excessive detergent causing foam — Using too much detergent, or a non-HE detergent in a high-efficiency machine, can generate foam that the pressure switch interprets as excess water. The machine may trigger E37 as a precaution even though the actual water volume is within normal limits.
Step-by-Step Fix
- 1
Switch off and isolate the machine
Turn the machine off at the control panel, then switch it off at the wall socket. Turn the water supply tap (usually behind or beneath the machine) to the fully closed position. This stops any further water entering and gives the inlet valve a chance to reset if it was temporarily stuck. Wait at least 10 minutes before proceeding.
- 2
Drain any excess water
Place a shallow tray under the filter access panel at the bottom front of the machine. Open the small emergency drain hose (if fitted) or unscrew the filter cap slowly to allow water to drain out in a controlled way. Remove any visible debris from the filter while you have it open. This step is important before you start inspecting internal components.
- 3
Check the detergent and run a test cycle
Make sure you are using the correct type and quantity of detergent for your machine — check the detergent drawer for any residue or foam build-up and clean it thoroughly. Reconnect the water supply, restart the machine on a short cotton cycle with no laundry and no detergent, and observe whether E37 returns. If it does not, excess foam was likely the cause.
- 4
Inspect the pressure switch hose
Pull the machine away from the wall and remove the top panel (usually two screws at the rear). Locate the thin rubber or plastic hose running from the bottom of the drum up to the pressure switch on the side of the cabinet. Check the full length of the hose for kinks, cracks, or blockages. Disconnect each end and blow through it gently — it should be completely clear. Reattach securely.
- 5
Test the pressure switch
With the top panel still removed, locate the pressure switch — a small round component with a single hose connection and two or three electrical terminals. Disconnect the hose and blow gently into the hose port; you should hear a faint click as the switch activates. No click suggests the switch has failed and needs replacing. You can also use a multimeter to test continuity across the terminals as you blow.
- 6
Inspect the water inlet valve
The inlet valve is located at the back of the machine where the fill hose connects. With the machine fully isolated from power and water, disconnect the fill hose and check the mesh filter inside the valve inlet for debris — clean it with a soft brush under running water. If the valve body feels wet on the outside or shows signs of corrosion, it is likely leaking internally and should be replaced.
- 7
Reset the machine and monitor
Reassemble all panels, reconnect water and power, and run a full cycle while staying nearby to observe. If E37 does not return and the machine fills and drains normally, the fault has been resolved. If the error reappears after completing all the above steps, the fault is likely with the inlet valve solenoid or the control board, and a service technician should be contacted.
Affected models
Select your model to see its full troubleshooting page.
When to call a service technician
If you have inspected the pressure switch hose, tested the pressure switch, and cleaned the inlet valve filter but E37 continues to appear, the inlet valve solenoid has most likely failed internally and is allowing water to pass through even when closed. Replacing a solenoid valve involves working with both the water supply and electrical connections, and if you are not confident doing this safely, a service technician should carry out the work.
You should also call a service technician if the machine is filling with water while switched off at the control panel — this is a clear sign of a valve that is no longer sealing, and it poses a flood risk. Similarly, if the control board is suspected, diagnosis requires specialist equipment and should not be attempted without experience.
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Frequently Asked Questions
Can I still use my Bosch washing machine while it shows E37?
No — you should not attempt to run a wash cycle while E37 is active. The error indicates the machine cannot reliably control its water level, which means there is a risk of overfilling and potential water damage to your home. Isolate the water supply and work through the troubleshooting steps before using the machine again.
Will turning the machine off and on again clear E37 permanently?
A power reset may clear the error temporarily, but if the underlying fault — a failed pressure switch or a leaking inlet valve — has not been fixed, the code will return during the next fill cycle. Use the reset only as a first diagnostic step, not as a long-term solution.
How do I know if it is the pressure switch or the inlet valve causing E37?
A useful distinction is whether the drum is actually overfilling or not. If you can see the water level is genuinely too high, the inlet valve is the more likely culprit. If the water level looks normal but the error still appears, the pressure switch or its hose is probably sending a false reading. Testing the pressure switch with a gentle blow and listening for a click is a quick way to check it without tools.
How much does it cost to replace a Bosch washing machine pressure switch?
Pressure switches for Bosch washing machines typically cost between £15 and £40 for the part, depending on the model. If you fit it yourself the total cost is just the part price. A service technician call-out will add labour costs on top, so it is worth attempting the replacement yourself if you are comfortable removing the top panel and disconnecting a hose and two or three electrical connectors.
Could hard water cause the E37 error on my Bosch washing machine?
Hard water itself does not directly trigger E37, but limescale build-up over time can partially block the mesh filter inside the inlet valve, causing it to behave erratically. Limescale can also affect the pressure switch hose if residue accumulates inside it. Running a monthly maintenance wash at 60°C with a descaling agent helps keep these components clear and extends their working life.