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Error code reference

Bosch Dryer Error Code E:12

Overheating (fluffing) level 2

Bosch codesBosch dryer codes

Overheating (fluffing) level 2 — heater temperature rose more than 7°C in 5 seconds 10 times; fluff filter, container or air routes blocked.

First step from the service manual

Clean components and air routes.

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

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What E:12 means on a Bosch dryer

The E:12 error code on a Bosch dryer indicates a Stage 2 overheating condition in the fluffing (tumbling) cycle. Specifically, the control board logs this fault when the heater temperature rises more than 7 degrees Celsius within a 5-second window, and this spike occurs 10 consecutive times. This pattern tells the control board that heat is accumulating abnormally fast, which points to restricted airflow rather than a failing heating element or thermostat producing runaway heat on its own.

The root cause in the vast majority of cases is a blockage somewhere in the dryer's air circuit. Bosch condenser dryers use a closed-loop airflow system that includes a fluff filter, a condenser unit, and internal air routes or ducting. When any of these become clogged with lint, debris, or compacted fluff, hot air cannot circulate and dissipate properly. The trapped heat causes rapid temperature spikes that the sensor detects repeatedly, eventually triggering E:12 to shut down the heating system and protect components.

On heat-pump dryer models, the evaporator and condenser fins are also part of this air circuit and are particularly vulnerable to lint buildup. The condensate container should also be checked, as an overfull container can restrict moisture removal and indirectly contribute to thermal buildup. Clearing all blocked components and air routes is the required first diagnostic step before suspecting any electrical or sensor-related fault.

Source: manufacturer service documentation.

Common causes of E:12

  1. 01

    Clogged fluff or lint filter

    Wiring / connection

    A heavily loaded lint filter restricts the primary airflow path, causing heat to build up quickly inside the drum. Remove and clean the filter thoroughly, checking that the filter housing itself is also free of compacted lint.

  2. 02

    Dirty or blocked condenser unit

    Wiring / connection

    The condenser collects moisture from the drum air and can become coated with fine lint over time, severely reducing airflow. Remove the condenser from its housing and rinse it under running water until the fins are clear.

  3. 03

    Blocked internal air routes or ducting

    Wiring / connection

    Lint can accumulate inside the internal air channels and ducting beyond the filter, especially around the fan housing. These passages need to be inspected and cleared to restore proper airflow circulation.

  4. 04

    Overfull condensate container

    Wiring / connection

    On condenser dryers, a full water container prevents the condenser from removing moisture effectively, which can contribute to heat buildup and trigger overheating faults. Empty and reinstall the container before running the dryer again.

  5. 05

    Faulty temperature sensor or NTC thermistor

    Part replacement

    If all airflow components are clean and the error persists, the temperature sensor responsible for monitoring heater output may be reading inaccurately and triggering false overheating events. Testing or replacing the sensor would be the next step.

See the test procedure for each cause

Frequently asked questions about E:12

What does E:12 mean on a Bosch dryer?
E:12 indicates a Stage 2 overheating fault during the fluffing cycle. The dryer's control board detected that the heater temperature rose more than 7 degrees Celsius within 5 seconds, and this occurred 10 times in a row. This pattern almost always points to blocked airflow caused by a clogged lint filter, dirty condenser, or obstructed internal air routes. The dryer shuts down the heating system automatically to prevent component damage.
How do I fix the E:12 error on my Bosch dryer?
Start by cleaning the fluff filter, the condenser unit, and all accessible internal air passages. Empty the condensate container if your model uses one. After cleaning all components, run a short cycle to see if the error clears. If E:12 returns after a thorough cleaning, a temperature sensor or NTC thermistor may need to be tested and potentially replaced.
Is it safe to keep using my Bosch dryer when E:12 appears?
No, you should not continue running the dryer while E:12 is active. The error means the dryer has detected repeated rapid overheating events and has shut down to protect itself. Running the machine in this condition risks damaging internal components and could create a fire hazard if the underlying airflow blockage is not resolved first.
Will resetting my Bosch dryer clear the E:12 error?
A power reset may clear the fault code temporarily, but the error will return if the root cause has not been addressed. The control board triggers E:12 based on a repeated pattern of temperature spikes, so as long as a blockage restricts airflow, the dryer will overheat again and re-enter the fault. Always clean the filter, condenser, and air routes before attempting a reset.
How much does it cost to repair a Bosch dryer showing E:12?
If the fix is simply cleaning the lint filter, condenser, and air routes, there is no parts cost involved and you can do it yourself at no charge. If a faulty temperature sensor or other component is confirmed as the cause after cleaning, parts and labor for a professional repair typically range from $100 to $250 depending on the specific part needed and local labor rates.

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