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Error code reference

Bosch Dryer Error Code E:27

Compressor

Bosch codesBosch dryer codes

Compressor - overheating error.

First step from the service manual

Clean interior of the appliance from fluffs.

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

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What E:27 means on a Bosch dryer

The E:27 error code on a Bosch dryer indicates a compressor overheating fault. Bosch heat pump dryers use a refrigerant-based compressor system instead of a traditional heating element, and this compressor is sensitive to thermal conditions. When the compressor's internal temperature exceeds safe operating thresholds, the control board triggers the E:27 code to protect the component from permanent damage. This is a protective shutdown, not a mechanical failure in itself, but it signals that something is preventing the compressor from cooling and operating within its design limits.

The most common trigger for this fault is lint and fluff accumulation inside the appliance. Heat pump dryers circulate air through a closed loop, and when lint builds up around the compressor housing, evaporator, or condenser coils, airflow is restricted and heat cannot dissipate properly. The compressor then runs hotter than intended and trips the overheat protection. Blocked filters, a clogged heat exchanger, or a poorly ventilated installation space can all contribute to this same thermal buildup.

Beyond lint accumulation, the fault can also result from ambient temperature conditions or a failing compressor that is drawing excessive current and generating excess heat internally. If cleaning all filters and the interior resolves the issue, no parts replacement is needed. If the error persists after thorough cleaning and adequate ventilation is confirmed, further diagnosis of the compressor, thermistor, or control board may be necessary.

Source: manufacturer service documentation.

Common causes of E:27

  1. 01

    Lint and fluff buildup inside the appliance

    Wiring / connection

    Accumulated lint around the compressor housing or heat exchanger restricts airflow and causes heat to build up rapidly. Inspect and clean the interior compartment, filters, and heat exchanger thoroughly.

  2. 02

    Clogged or dirty heat exchanger or condenser

    Wiring / connection

    The condenser coils in a heat pump dryer must be kept clean to release heat efficiently. If the condenser fins are coated with lint or debris, the compressor will overheat even if the drum filter appears clean.

  3. 03

    Poor ventilation around the dryer

    Wiring / connection

    If the dryer is installed in a confined space without adequate clearance, ambient heat accumulates and the compressor cannot cool properly. Verify that the installation meets the minimum clearance requirements specified for the unit.

  4. 04

    Faulty compressor overheating internally

    Part replacement

    A compressor that is worn or failing may generate excessive heat during operation even in clean, well-ventilated conditions. If the error returns immediately after cleaning and conditions are otherwise correct, compressor replacement should be evaluated by a technician.

  5. 05

    Defective thermistor or temperature sensor

    Part replacement

    A faulty thermistor monitoring the compressor temperature may send inaccurate readings to the control board, triggering a false overheat fault. This requires testing the sensor for correct resistance values and replacing it if readings are out of range.

See the test procedure for each cause

Frequently asked questions about E:27

What does E:27 mean on a Bosch dryer?
E:27 on a Bosch dryer means the compressor has overheated and the appliance has shut down to prevent damage. Bosch heat pump dryers rely on the compressor to circulate refrigerant and generate heat, and when that component runs too hot, the control system triggers this protective fault. The most common cause is lint buildup restricting airflow inside the machine. Cleaning the interior and filters is the recommended first diagnostic step.
Can I fix the E:27 error myself, or do I need a technician?
In many cases, the E:27 error can be resolved without a technician by thoroughly cleaning lint from the interior of the dryer, including the filters and heat exchanger. If the error clears after cleaning and does not return, no further action is needed. However, if the fault persists after cleaning or reappears quickly during normal use, a technician should inspect the compressor and temperature sensors.
Is it safe to keep using my Bosch dryer when E:27 is displayed?
No, you should not continue running the dryer while E:27 is active. The code indicates the compressor has already exceeded safe operating temperatures, and running the appliance in this condition risks permanent damage to the compressor. Allow the dryer to cool down completely, clean the interior, and only restart it once the root cause has been addressed.
Will resetting the dryer clear the E:27 error code?
A reset may clear the fault code temporarily and allow the dryer to start again, but if the underlying cause, typically lint buildup or restricted airflow, has not been corrected, the error will return. Always clean the interior and filters before attempting a reset to avoid repeated compressor shutdowns that could eventually cause permanent component damage.
How much does it cost to repair a Bosch dryer showing E:27?
If the issue is lint accumulation, the repair cost is minimal and involves only your time for cleaning. If a thermistor or sensor needs replacement, parts and labor typically range from $100 to $250 depending on your location and service provider. Compressor replacement is a more significant repair and can range from $300 to $600 or more, at which point it may be worth comparing repair cost against appliance replacement.

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