Bosch F27 Error Code - Causes & Fix

What this code means

The F27 error code on a Bosch washing machine indicates a fault in the pressure sensor or pressure-sensing circuit. This sensor monitors the water level inside the drum. When it fails or cannot communicate properly with the control board, the washer cannot determine how much water is present and will stop the cycle to prevent overfilling or underfilling.

Bosch states that this fault cannot be rectified by the user and recommends arranging service. The code points to a problem with the pressure switch itself, the plastic pressure tube that connects it to the tub, the wiring harness, or in rare cases the control module. The machine may not fill, may overfill, or may simply halt mid-cycle when the sensor reading is out of range.

Before You Replace Anything

Many people replace the control board first, assuming an electronics fault. Before ordering a new board, inspect and clear the pressure tube and test or swap the pressure switch. Most F27 codes are resolved by replacing the inexpensive switch or reconnecting a loose hose.

Common Causes

• Faulty pressure sensor or pressure switch The sensor itself has failed internally and no longer sends accurate water-level signals to the control board.
• Blocked, kinked, or disconnected pressure tube The small plastic hose that runs from the outer tub to the pressure switch is obstructed by detergent residue, lint, or has come loose from its fitting.
• Corroded or loose wiring connector at the pressure switch Moisture or vibration has damaged the electrical plug or terminals, interrupting the signal path to the control board.
• Restricted water inlet or low supply pressure A closed tap, clogged inlet screen, or kinked inlet hose prevents proper filling, causing the sensor to time out or read incorrectly.
• Control board input circuit failure A trace or relay on the main PCB has failed in the pressure-sensor input stage, though this is much less common than a failed switch.

Step-by-Step Fix

1. Unplug the washer and turn off both hot and cold supply taps to make the workspace safe.
2. Remove the top or rear panel (consult your model’s service manual) to access the pressure switch, which is usually mounted high on the side or rear wall of the cabinet.
3. Inspect the pressure tube that runs from a nipple on the outer tub or sump up to the pressure switch. Look for kinks, cracks, or detergent buildup inside. Disconnect it and blow through it to confirm it is clear.
4. Check the electrical connector on the pressure switch for corrosion, loose pins, or moisture. Clean contacts with electrical contact cleaner if needed.
5. Test or replace the pressure switch. If you have a multimeter and your model’s wiring diagram lists resistance or continuity values, measure across the switch terminals. Otherwise, install a new switch that matches your model number.
6. Reconnect all hoses and wiring, replace the panel, restore power and water, then run a rinse or spin cycle to verify the error has cleared.
7. If the F27 persists after confirming the tube is clear and the switch is new, inspect the wiring harness between the switch and control board. If that harness is intact, the control board input circuit may be faulty and will require professional board-level repair or replacement.

Parts Often Needed

When to Call a Pro

Call a professional if you are uncomfortable removing panels, working around electrical connectors, or identifying components inside the washer cabinet. Also arrange service if you have already replaced the pressure switch and cleared the pressure tube but the F27 code returns. At that point the fault is likely in the wiring harness or on the control board, and a technician with a schematic and meter can isolate the failure quickly. Bosch explicitly states that this error cannot be rectified by the user and recommends arranging service, so warranty or in-warranty machines should be reported to an authorized service center rather than opened at home.