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Error code reference

Bosch Washer Error Code Er:21

Drain pump time exceeded.

Bosch codesBosch washer codes

Drain pump time exceeded.

First step from the service manual

Check drain pump, wire harness, and drain hose.

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

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What Er:21 means on a Bosch washer

Er:21 on a Bosch washer indicates that the drain pump exceeded its allotted operating time without successfully evacuating water from the tub. The control board monitors how long the drain pump runs during each drain cycle. When the pump runs beyond the programmed time limit without completing the drain, the board triggers this fault and halts the cycle to prevent motor burnout or flooding conditions.

The drain pump, wire harness connections, and drain hose are the primary components involved. A clogged pump filter or blocked drain hose restricts flow and forces the pump to run longer than expected. A failing pump motor may spin too slowly or not at all, preventing adequate water removal. Wiring faults, including corroded terminals or a broken wire in the harness, can interrupt the signal to the pump entirely, meaning the pump never receives full power.

Less commonly, a kinked or improperly routed drain hose creates back pressure that slows drainage. If the standpipe or household drain connection is clogged, water cannot exit even if the pump is functioning correctly. Technicians should begin by inspecting the pump filter for debris, verifying the drain hose has no kinks or blockages, and checking harness connectors at the pump for corrosion or loose pins before condemning the pump motor itself.

Source: manufacturer service documentation.

Common causes of Er:21

  1. 01

    Clogged drain pump filter

    Wiring / connection

    Lint, coins, and debris accumulate in the pump filter and restrict water flow, forcing the pump to run past its time limit. The filter is typically located behind a small access panel at the front lower section of the washer.

  2. 02

    Blocked or kinked drain hose

    Wiring / connection

    A drain hose that is kinked, crushed, or clogged with buildup prevents water from exiting the machine at the required flow rate. Inspect the full length of the hose from the pump outlet to the standpipe or sink connection.

  3. 03

    Faulty drain pump motor

    Part replacement

    A worn or failed pump motor will not spin at sufficient speed to move water out of the tub within the allotted time. If the filter and hose are clear but drainage is still slow or absent, the pump motor is likely the cause.

  4. 04

    Damaged or faulty wire harness

    Part replacement

    Corroded terminals, broken wires, or loose connector pins in the harness between the control board and drain pump can reduce or cut power to the pump. Inspect the connector at the pump body for signs of heat damage, corrosion, or a loose fit.

  5. 05

    Clogged household drain or standpipe

    Wiring / connection

    If the external drain connection is blocked, water cannot exit even if the pump is working properly. Check whether other nearby drains in the home are also draining slowly.

See the test procedure for each cause

Frequently asked questions about Er:21

What does Er:21 mean on a Bosch washer?
Er:21 means the drain pump ran longer than the control board's programmed time limit without successfully draining the tub. The washer stops the cycle automatically to prevent damage. This code points to a problem in the drain system, which includes the pump, the drain hose, and the wire harness connecting the pump to the control board.
Can I fix Er:21 on my Bosch washer myself?
Many cases of Er:21 can be resolved without professional help. Start by cleaning the drain pump filter and checking the drain hose for kinks or blockages, as these are the most common causes. If those steps do not resolve the issue, testing or replacing the drain pump motor or inspecting the wire harness may require more technical skill and specialized tools.
Is it safe to keep using my Bosch washer when Er:21 appears?
No, you should not continue running the washer until the fault is resolved. Er:21 indicates water is not draining properly, and running a cycle with standing water in the tub can stress the motor and other internal components. There is also a risk of water remaining in the drum and causing mold or mildew buildup.
Will resetting my Bosch washer clear the Er:21 code?
Resetting the washer may temporarily clear the error code, but it will return if the underlying drainage problem is not corrected. To reset, you can power the machine off and back on or unplug it for a few minutes. The code will reappear on the next drain cycle if the clog, hose issue, or pump fault has not been addressed.
How much does it cost to repair a Bosch washer with an Er:21 error?
Repair costs vary depending on the cause. Cleaning a clogged pump filter costs nothing beyond your time. Replacing a drain pump motor typically runs anywhere from $80 to $200 or more for parts alone, with labor adding to the total if a technician is involved. Wiring harness repairs generally fall in a similar range depending on the extent of the damage.

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