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Error code reference

Bosch Washer Error Code 31

Overflow level exceeded

Bosch codesBosch washer codes

Overflow level exceeded - solenoid valve stuck, pressure sensor adjustment incorrect, pressure sensor or hose blocked.

First step from the service manual

Check solenoid valve, check pump, check pressure sensor, check hose to pressure sensor, check wire harness, check draining hose.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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  • Wiring diagram references and connector pinouts from the OEM service manual
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What 31 means on a Bosch washer

Error code 31 on a Bosch washer indicates that the water level inside the drum has exceeded the overflow threshold. The machine's pressure sensor, also called the pressure switch or water level sensor, continuously monitors drum water level by detecting air pressure changes in a connected hose. When the control board receives a signal indicating water has risen above the maximum safe level, it triggers code 31 and halts operation to prevent flooding or mechanical damage.

The most common hardware cause is a stuck or faulty water inlet solenoid valve. This valve is responsible for opening and closing the water supply to the tub. If it fails in the open position, water continues entering the drum even when the control board sends a signal to stop filling. A defective solenoid valve will typically require replacement. Additionally, the pressure sensor itself may be miscalibrated or blocked, causing it to misread the actual water level. The small hose connecting the drum to the pressure sensor can accumulate detergent residue, lint, or debris, which restricts airflow and causes inaccurate pressure readings.

Diagnostic steps should cover the full water control circuit. Start by inspecting the solenoid valve for mechanical or electrical failure, then check the pressure sensor and its connecting hose for blockages or damage. The wire harness connecting these components should be examined for corrosion, breaks, or loose terminals. The drain pump should also be tested, since a pump that fails to remove water can contribute to elevated water levels. Finally, verify the drain hose routing to ensure it is not positioned in a way that causes siphoning or backflow into the drum.

Source: manufacturer service documentation.

Common causes of 31

  1. 01

    Stuck inlet solenoid valve

    Part replacement

    The water inlet solenoid valve may be mechanically stuck in the open position, allowing water to continuously enter the tub. You can test the valve coils for proper resistance with a multimeter and inspect the valve body for debris preventing it from closing.

  2. 02

    Blocked pressure sensor hose

    Wiring / connection

    The small hose that runs from the drum to the pressure sensor can become clogged with detergent buildup or lint, causing inaccurate water level readings. Disconnect and inspect the hose for blockages and clear it with compressed air or by rinsing it out.

  3. 03

    Faulty or miscalibrated pressure sensor

    Part replacement

    The pressure sensor itself may be out of adjustment or defective, causing it to report an overflow condition even when the actual water level is normal. Check the sensor connections and test the component for correct operation.

  4. 04

    Drain pump failure

    Part replacement

    If the drain pump is not removing water effectively, water can accumulate to overflow levels even if the inlet valve is functioning correctly. Listen for the pump running during the drain cycle and inspect it for blockages or electrical faults.

  5. 05

    Wire harness damage or loose connections

    Wiring / connection

    Corroded, broken, or loose wiring between the control board, solenoid valve, and pressure sensor can cause incorrect signals and trigger a false overflow error. Visually inspect the harness and connectors for damage or poor seating.

See the test procedure for each cause

Frequently asked questions about 31

What does 31 mean on a Bosch washer?
Error code 31 means the washer has detected that the water level in the drum has exceeded the overflow limit. The control board monitors water level through a pressure sensor and halts the cycle when that limit is reached. Common causes include a stuck inlet solenoid valve, a blocked pressure sensor hose, or a faulty pressure sensor. The machine stops itself automatically to prevent water damage.
Will resetting the washer clear error code 31?
A reset may temporarily clear the code and allow the machine to restart, but if the underlying problem is not repaired, the error will return during the next fill cycle. If the solenoid valve is stuck open or the pressure sensor hose is blocked, these issues must be physically corrected before the washer will run normally. Always diagnose the root cause before relying on a reset.
Is it safe to use my Bosch washer when it shows error code 31?
You should not continue using the washer until the cause of code 31 is identified and corrected. An overflow condition can lead to water leaking onto the floor, which creates slip hazards and potential damage to surrounding cabinetry and flooring. The machine's automatic shutoff is a safety feature, and bypassing or ignoring it is not recommended.
How do I fix error code 31 on a Bosch washer?
Start by inspecting the pressure sensor hose for blockages or kinks, as this is a no-parts fix you can perform yourself. Next, check the water inlet solenoid valve to see if it is stuck open or failing electrically. Inspect the wire harness for damaged or loose connections. If the pressure sensor itself is faulty or miscalibrated, or if the solenoid valve needs replacement, those parts will need to be sourced and installed.
How much does it cost to repair error code 31 on a Bosch washer?
Repair costs vary depending on which component has failed. If only the pressure sensor hose needs cleaning, there may be no parts cost and minimal labor. Replacing a water inlet solenoid valve typically costs between $40 and $120 for the part, while a pressure sensor replacement generally falls in the $30 to $90 range. Adding professional labor brings the total repair estimate to roughly $100 to $300 depending on your location and the technician's rates.

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