What does the E20 error code mean on a Bosch dishwasher?

The E20 error code on a Bosch dishwasher means the appliance has detected water remaining in the tub after the drain cycle has completed. This is typically caused by a clogged filter, a blocked or kinked drain hose, a faulty drain pump, or a blocked air gap. The dishwasher stops the cycle to prevent overflow or further damage.

What does the E21 error code mean on a Bosch dishwasher?

The E21 error code on a Bosch dishwasher indicates a slow or restricted drain. Unlike E20, water is still draining but not at the required rate. This is most often caused by a partially clogged filter, a partially blocked drain pump impeller, or debris buildup in the drain path that reduces water flow without completely stopping it.

What is the difference between E20, E21, E24, and E25 on a Bosch dishwasher?

All four codes relate to drainage issues but at different levels of severity and specificity. E20 means water is not draining at all after the cycle. E21 means water is draining too slowly. E24 indicates a general drainage failure detected during the cycle. E25 points specifically to a blocked drain pump or an improperly fitted pump cover. Identifying the exact code helps narrow down the correct repair.

How do I fix the E20 or E21 error on my Bosch dishwasher?

Start by cleaning the filter assembly at the bottom of the dishwasher tub thoroughly. Then check the drain hose for kinks, blockages, or improper routing. Inspect the drain pump area for debris caught in the impeller. Also check the sink drain or garbage disposal connection for blockages. If these steps do not resolve the error, the drain pump motor may need professional inspection or replacement.

Does Promix Appliance Repair fix Bosch dishwasher E20 and E21 errors in Boston?

Yes. Promix Appliance Repair provides same-day Bosch dishwasher repair services throughout Boston, Newton, Needham, Brookline, Wellesley, and surrounding areas. Call (781) 666-9565 to book a same-day appointment.

E20
E21

Bosch · Dishwasher · Error Code

Bosch Dishwasher E20 / E21 Error Codes — Circulation Pump Electrical Fault or Blockage

Technician Recommended Also shown as: E 20 E 21 E:20 E:21

Quick Answer

E20 and E21 both point to a fault in the circulation pump — the motor that pushes wash water through the spray arms during a cycle (not the drain pump). E20 is an electrical fault in the pump motor winding; E21 is a mechanical blockage preventing the pump from reaching the correct speed. Start with a breaker reset and a filter clean — these free steps resolve a meaningful share of cases by clearing temporary faults and relieving pump overload. If the code returns, a debris jam in the pump impeller is the next most likely cause for E21. An E20 that persists after a reset almost always requires a technician to test and replace the circulation pump or control board.

E20

Electrical fault — pump winding

A short circuit or open break in the circulation pump motor winding produces incorrect resistance. The control board detects the anomaly and stops the cycle. Symptoms: cycle stops early, no water circulating, machine silent mid-wash.

E21

Mechanical blockage — pump impeller

A blockage between the motor and pump housing prevents the impeller from reaching normal speed. The board sees insufficient water flow and raises E21. Symptoms: brief grinding noise at start, cycle stops within minutes, dishes not getting wet.

E09

Heating element fault — water doesn't heat. Different component but same thermal system family.

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E20 / E21

Circulation pump winding fault (E20) or circulation pump blockage (E21).

E19

Heat exchanger fault — thermal management component fault in same code family.

Time

10 min–2 hrs

Difficulty

Moderate–Hard

Tools

Multimeter, Torx set

DIY Cost

Free–$150

What E20 and E21 Mean

The circulation pump (also called the wash pump) is the motor that draws water from the sump and forces it at pressure through the spray arms during a wash or rinse cycle. It is a completely different component from the drain pump — its job is to circulate wash water around the tub, not to remove it. E20 and E21 both indicate a problem with this circulation pump specifically.

E20 is an electrical fault: a short circuit or broken winding in the circulation pump motor produces resistance values outside the expected range. The control board detects the discrepancy and halts the cycle to prevent further damage. Symptoms include the dishwasher going quiet mid-cycle without the sound of water spraying, cycles stopping very shortly after starting, and dishes completely dry and unsprayed when the door is opened.

E21 is a mechanical fault: a blockage between the motor shaft and the pump housing is preventing the impeller from reaching its normal rotational speed. The board detects insufficient water flow — confirming the pump is not circulating correctly — and stops with E21. The tell-tale sound is a brief grinding or buzzing at the very start of a wash phase, followed by silence and the error code. A small hard object — a glass fragment, seed, or bone chip that passed through the filter — is the most common culprit.

Both codes belong to the same thermal and pump management fault family as E19 (heat exchanger) and sit adjacent to E09 (heating element). They share the same first-line troubleshooting steps: a breaker reset and a thorough filter clean. For E21 specifically, inspecting and clearing the circulation pump impeller is a productive next step that a confident DIYer can attempt. A confirmed E20 winding fault or a seized E21 pump that can't be cleared by debris removal almost always requires a technician.

Common Causes — Most Likely First

Temporary control board fault from a power event.Both A voltage spike, power outage, or tripped breaker mid-cycle can produce a false E20 or E21 reading without any component having physically failed. A 5-minute breaker reset is always the first step. Common

Foreign object jammed in the circulation pump impeller.E21 primary A glass shard, bone chip, fruit stone, or small label has passed through the filter and lodged between the impeller blades. The pump tries to spin, makes a grinding noise, then the board shuts it down and raises E21. Very common for E21

Clogged filter overloading the circulation pump.Both A severely blocked filter makes the circulation pump work much harder to draw water from the sump. The increased motor load can produce both a flow-fault (E21) and in severe cases stress the motor winding enough to trigger E20. Cleaning the filter is always the first physical check. Common

Failed or shorted circulation pump motor winding.E20 primary The motor's copper winding coils have developed a short circuit or open break — the electrical path is broken or incorrectly completed. A multimeter test across the motor terminals will show out-of-range resistance. Motor replacement is required. Occasional — needs technician

Limescale buildup on the heat pump / circulation system.Both In hard-water areas, scale accumulates inside the pump housing and on the impeller over time, progressively restricting impeller movement and increasing motor load. A descaling treatment can improve this if caught early; advanced scaling requires pump servicing or replacement. Occasional

Loose or corroded wiring to the circulation pump.E20 related A deteriorated or unseated connector in the wiring harness between the control board and the pump motor introduces resistance or breaks the circuit, causing the board to read the pump's electrical signature as a fault. Occasional

Faulty control board misreading pump signals.Both The control board's pump monitoring circuit has developed an internal fault and is raising E20 or E21 even when the pump motor is operating normally. Confirmed only after the pump tests fine — board replacement is needed. Less common

How to Fix E20 / E21 — Step by Step

Reset the circuit breaker for at least 5 minutes

Trip the dishwasher's circuit breaker and leave it off for a full 5 minutes. This gives the control board's capacitors time to fully discharge and clears any transient fault state in the pump monitoring circuit. Restore power and run a full normal wash cycle before moving on to any physical checks. If the cycle completes without E20 or E21, a power event was the cause — monitor for recurrence.

If the code returns on the next cycle, the fault is hardware-based. Continue with the steps below.

Clean the filter assembly thoroughly

A heavily clogged filter forces the circulation pump to work much harder, and the increased current draw can mimic both E20 and E21 symptoms. Remove and rinse all three filter components — the cylindrical mesh filter, the flat coarse filter, and the fine mesh floor panel — under warm running water with a soft brush. Even if the filters look passable, a proper clean eliminates them as a contributing cause before you investigate the pump itself.

Run a descaling cycle (if in a hard-water area)

Limescale buildup on the pump internals is a realistic contributor to E21 in areas with hard tap water. Run an empty cycle on the hottest setting with a commercial dishwasher descaler or two cups of white vinegar placed in the base of the tub. This is a low-effort step that can restore some pump performance and is worth doing before any physical disassembly.

Inspect the circulation pump impeller for debris (E21 focus)

If E21 is the specific code and the reset and filter clean haven't resolved it, the circulation pump impeller likely has debris jammed in it. On most Bosch models the circulation pump is accessible from inside the tub through the sump area after filter removal — look for the larger pump housing distinct from the drain pump. With the power fully off and rubber gloves on, carefully reach into the housing opening and feel for any hard object lodged between the impeller blades. Remove anything you find. Try rotating the impeller by hand — it should turn with smooth, moderate resistance. A completely seized impeller indicates either a hard jam or internal motor failure.

Model-specific access: On some Bosch models the circulation pump can only be accessed from below by pulling the machine out and removing the base panel. If you can't reach the impeller from the sump opening, the steps below are a technician job.

Inspect wiring connections to the circulation pump (E20 focus)

With the dishwasher fully disconnected from power, access the circulation pump wiring — typically by removing the inner door panel or the base kickplate depending on the model. Check that the wiring harness connector at the pump motor is firmly seated and that the wire insulation shows no signs of burning, chafing, or corrosion at the terminals. Reseat any loose connectors. A burnt smell near the wiring or pump is a sign of a motor winding failure.

Test the circulation pump motor with a multimeter (E20)

With the machine fully disconnected from power and water, a confident DIYer can test the circulation pump motor for a winding fault. Disconnect the pump's electrical terminals and measure resistance across them with a multimeter set to ohms. A working Bosch circulation pump motor typically reads in a specific range for your model (check your tech sheet — commonly 100–300 Ω). A reading of zero (short circuit) or OL (open break) confirms a failed winding and the pump needs replacement.

Book a technician for pump or board replacement

If the reset, filter clean, and accessible impeller check haven't resolved the code, the circulation pump motor has failed (E20 winding fault), is physically seized beyond what debris removal can fix (E21), or the control board itself is misreading the pump signal. Circulation pump replacement on most Bosch models requires pulling the machine out and working from below — a moderately involved repair that most homeowners find better handled by a certified technician.

When to Call a Technician

A breaker reset and filter clean are the productive DIY steps for both codes. Book a professional repair if:

E20 or E21 returns after a full 5-minute breaker reset and thorough filter clean
A brief grinding or buzzing sound at cycle start followed by silence and E21 — the impeller is jammed and may need internal access from below the machine
No water appears to be spraying from the arms at any point in the cycle
The circulation pump motor tests as shorted or open on a multimeter (E20 confirmed)
The impeller is accessible and cleared of debris but E21 still returns — the motor may be internally seized
A burnt smell is detectable near the pump or wiring harness
Dishes come out completely dry and unsprayed despite the machine completing a full cycle time

Repair Cost Expectations

If You Fix It Yourself

Free–$150

Breaker reset, filter clean, and descaling cost nothing. A replacement circulation pump assembly for most Bosch models runs $80–$150 as a DIY part.

Professional Repair

$200–$450

Typical range in the Boston area for circulation pump diagnosis and replacement or control board repair — parts and labor included. Pump replacement with base-panel access tends toward the higher end.

Still Getting E20 or E21? We'll Fix Your Bosch Dishwasher.

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Frequently Asked Questions

What is the difference between E20 and E21 on a Bosch dishwasher?

Both codes point to the circulation pump — the motor that sprays wash water through the arms during a cycle — but they identify different types of fault. E20 is an electrical fault: an incorrect resistance reading in the pump motor winding, indicating a short circuit or broken coil. E21 is a mechanical fault: a blockage between the motor and pump housing that prevents the impeller from reaching normal speed, resulting in insufficient water flow. The tell-tale sign for E21 is a brief grinding or buzzing noise right at the start of a wash phase before the machine goes quiet.

What is the difference between the circulation pump (E20/E21) and the drain pump (E23/E25)?

They are two completely separate motors with different jobs. The circulation pump — the one E20 and E21 point to — pushes wash water up through the spray arms during a cycle. The drain pump — the one E23 and E25 point to — removes wastewater from the tub at the end of each phase. A machine with an E20 or E21 fault will typically have no standing water (it may have drained normally) but dishes will be completely unsprayed and unwashed. A machine with an E23 or E25 fault usually has standing water at the bottom of the tub.

Why does E21 sometimes produce a grinding noise at the start of a cycle?

When a hard object — a glass shard, fruit stone, or bone chip — is lodged in the circulation pump impeller, the motor attempts to spin up at the beginning of a wash phase. The impeller engages the obstruction, creates resistance, and the grinding or buzzing sound is the motor fighting against that resistance before the control board detects the fault current spike and shuts the motor off. This often happens within the first 60–90 seconds of a cycle.

Can I descale my dishwasher to fix E20 or E21?

Descaling is worth trying as a low-cost first step, particularly for E21 in hard-water areas. Limescale buildup on the pump internals gradually restricts the impeller's movement and increases the motor load. Running an empty cycle with a commercial descaler or white vinegar can dissolve mild scale accumulation and restore some pump performance. It won't repair a failed motor winding (E20) or remove a hard foreign object from the impeller (E21), but it's a productive step that costs very little to attempt.

How much does it cost to fix an E20 or E21 error?

A breaker reset, filter clean, and descaling cycle cost nothing. A replacement circulation pump assembly as a DIY part runs $80–$150 for most Bosch models. Professional repair in the Boston area for circulation pump diagnosis and replacement typically runs $200–$450, parts and labor included, with jobs requiring base-panel access trending toward the higher end.