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Error code reference

Bosch Washer Error Code F:27

Error of offset adjustment of analogue pressure sensor

Bosch codesBosch washer codes

Error of offset adjustment of analogue pressure sensor - pressure sensor is broken; adjustment will be skipped and old value used.

First step from the service manual

Check pressure sensor, check wire harness.

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

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What F:27 means on a Bosch washer

The F:27 error code on a Bosch washer indicates a failure in the offset adjustment process of the analog pressure sensor, also called the water level sensor or pressure transducer. During each wash cycle, the control board performs an offset calibration on this sensor to establish a baseline air pressure reading before water enters the drum. When the board detects that the sensor's output signal falls outside the acceptable calibration range, it flags F:27, skips the adjustment routine, and falls back on the last stored calibration value instead of using a fresh reading.

The analog pressure sensor works by detecting changes in air pressure within a small air trap and hose connected to the drum. As water fills the drum, it compresses the air in this chamber, and the sensor converts that pressure into a variable voltage signal the control board interprets as water level. A broken or degraded sensor may produce a voltage signal that is stuck, erratic, or out of range, making accurate offset calibration impossible. This can cause the washer to misjudge water levels, leading to overfilling, underfilling, or cycle interruptions.

The primary diagnostic path involves inspecting the pressure sensor itself and the wire harness connecting it to the main control board. Damaged wiring, corroded connectors, or a pinched harness can distort the sensor's signal even if the sensor component itself is functional. If the wiring checks out, the sensor should be tested directly and replaced if it fails to produce a stable, accurate signal within the expected parameters.

Source: manufacturer service documentation.

Common causes of F:27

  1. 01

    Faulty analog pressure sensor

    Part replacement

    The pressure sensor itself may be internally damaged, producing a signal that falls outside the expected calibration range. This is the most direct cause of F:27 and is confirmed by testing the sensor's output voltage or replacing it.

  2. 02

    Damaged or corroded wire harness

    Wiring / connection

    The wiring between the pressure sensor and the control board may be broken, pinched, or have corroded connector pins. Inspect the harness visually and check for continuity at each pin to rule this out before replacing the sensor.

  3. 03

    Loose or disconnected connector at the sensor

    Wiring / connection

    The connector at the pressure sensor port can work itself loose over time due to vibration. A partially seated connector produces an intermittent or out-of-range signal that triggers the calibration failure.

  4. 04

    Blocked or kinked pressure hose

    Wiring / connection

    The small rubber hose connecting the air trap to the pressure sensor can become kinked, clogged with detergent residue, or cracked. A blocked hose prevents accurate pressure transmission to the sensor, which can disrupt the calibration process.

  5. 05

    Main control board fault

    Part replacement

    If the sensor, harness, and pressure hose all test correctly, a fault on the main control board may be preventing proper signal interpretation during the offset adjustment routine. This is the least common cause and should be considered after all other components are confirmed good.

See the test procedure for each cause

Frequently asked questions about F:27

What does F:27 mean on a Bosch washer?
F:27 indicates that the washer's control board failed to complete the offset calibration of the analog pressure sensor, which is the component responsible for measuring the water level inside the drum. The error means the sensor produced a signal the board could not use for calibration, so it skipped the adjustment and retained the last saved value. The code points to either a broken pressure sensor or a problem with the wiring harness connected to it.
Can I fix F:27 on my Bosch washer myself?
Some causes of F:27 are accessible to a confident DIYer, such as reseating a loose connector, inspecting the wire harness for visible damage, or clearing a kinked pressure hose. If the sensor itself needs to be replaced, the repair requires disconnecting power, accessing the sensor inside the machine, and installing a compatible replacement part. Checking the wiring and hose first is always the recommended starting point before purchasing any components.
Is it safe to keep using my washer when F:27 is displayed?
Continuing to run the washer with an active F:27 code is not recommended. Because the machine is relying on an old stored calibration value rather than a live sensor reading, it may misjudge the water level and risk overfilling or not filling correctly. Running cycles under these conditions could lead to water leaks or poor wash performance, so the issue should be diagnosed before further use.
Will resetting my Bosch washer clear the F:27 error?
A reset may temporarily clear the F:27 display, but the error will return as soon as the machine attempts to calibrate the pressure sensor again at the start of the next cycle, assuming the underlying fault has not been fixed. Resetting is useful for confirming whether the problem is persistent, but it does not address the cause. The sensor and wiring need to be inspected and repaired or replaced to resolve the code permanently.
How much does it cost to repair a Bosch washer F:27 error?
If the repair involves only reseating a connector or clearing a kinked hose, there may be no parts cost at all, though a service call from a technician would typically run in the range of $80 to $150 for labor. Replacing the analog pressure sensor itself generally costs between $20 and $60 for the part, with additional labor charges if a technician performs the work. A main control board replacement, if required, is significantly more expensive, often ranging from $150 to $350 or more for parts and labor combined.

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