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Error code reference

Bosch Dryer Error Code E:4

Time error

Bosch codesBosch dryer codes

Time error — drying cycle exceeded allowed time.

First step from the service manual

1) User must reduce load or choose other program. 2) Check compressor circuit / overload protector switch.

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

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What E:4 means on a Bosch dryer

The E:4 error code on a Bosch dryer indicates a time error, meaning the drying cycle has run longer than the maximum permitted duration without reaching the target dryness level. The control board monitors how long each cycle runs and triggers this fault when the elapsed time exceeds the programmed threshold. This is a protective function designed to prevent the dryer from running indefinitely, which could indicate an underlying problem preventing effective moisture removal.

The most common trigger for E:4 is an oversized or excessively wet load that the dryer cannot process within the allowed time window. Heat pump dryers, which Bosch commonly produces, rely on a refrigerant-based compressor circuit to extract moisture from the drum air. If the compressor is not operating correctly, or if the overload protector switch on the compressor circuit has tripped, the dryer loses its primary moisture-removal capability and the cycle runs on without completing.

Diagnosis should begin by reducing the load size or selecting a different drying program to rule out user error. If the error persists with a normal load, attention should shift to the compressor circuit. A tripped overload protector will prevent compressor operation entirely, and this component must be tested and replaced if faulty. The refrigerant circuit, compressor motor windings, and associated wiring should also be inspected for faults that could reduce drying efficiency below the threshold needed to complete a cycle in time.

Source: manufacturer service documentation.

Common causes of E:4

  1. 01

    Overloaded or excessively wet load

    Wiring / connection

    Placing too many items or very heavy wet laundry in the drum forces the dryer to work beyond its time limit. Reducing the load size and restarting the cycle will clear this cause if no hardware fault is present.

  2. 02

    Tripped or failed compressor overload protector

    Part replacement

    The overload protector switch on the compressor circuit can trip due to heat or electrical stress, cutting power to the compressor and halting moisture extraction. The switch must be tested for continuity and replaced if it has failed open.

  3. 03

    Compressor circuit fault

    Part replacement

    A fault within the compressor circuit itself, including wiring issues or a failing compressor motor, will prevent the heat pump system from removing moisture efficiently. This requires electrical testing of the circuit components to identify the specific failure point.

  4. 04

    Wrong program selected for load type

    Wiring / connection

    Choosing a program with a shorter time allowance than the load requires can trigger E:4 even when the machine is functioning correctly. Selecting a program appropriate for the fabric type and load weight will resolve this.

  5. 05

    Restricted airflow or clogged filter

    Wiring / connection

    Reduced airflow caused by a blocked lint filter or condenser unit limits drying efficiency and can cause cycles to run past the time limit. Cleaning the lint filter and condenser regularly is part of routine maintenance for Bosch heat pump dryers.

See the test procedure for each cause

Frequently asked questions about E:4

What does E:4 mean on a Bosch dryer?
E:4 is a time error indicating the drying cycle exceeded the maximum allowed run time without completing. The dryer triggers this fault as a protective measure to prevent it from running indefinitely. It can result from an oversized load, an incorrect program selection, or a fault in the compressor circuit that reduces the machine's ability to remove moisture from the drum.
How do I fix E:4 on my Bosch dryer?
Start by reducing the size of your load and selecting the appropriate drying program for the fabric type, then run the cycle again. If the error clears, an overloaded drum was the cause. If E:4 returns with a normal load, the compressor overload protector switch or broader compressor circuit should be inspected and tested by a qualified technician.
Will resetting the dryer clear the E:4 error?
A reset may clear the displayed error code temporarily, but it will not resolve an underlying hardware fault. If the compressor circuit or overload protector has failed, E:4 will return as soon as the dryer attempts another cycle. A reset is worth trying after reducing the load, but persistent errors require component-level diagnosis.
Is it safe to keep using my Bosch dryer when E:4 is showing?
The dryer stops itself when E:4 triggers, so it is not actively running in a dangerous state. However, continuing to use the machine without addressing the root cause is not advisable if the error is related to a compressor fault. Repeated operation with a faulty compressor circuit can cause additional damage to related components.
How much does it cost to repair a Bosch dryer showing E:4?
If the fix is simply adjusting load size or program selection, there is no cost involved. Replacing a compressor overload protector switch typically falls in the range of $50 to $150 including parts and labor, depending on the specific model and service rates in your area. A compressor replacement is a more significant repair and costs considerably more, generally in the range of $200 to $500 or higher.

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