E27

Bosch · Dishwasher · Error Code

Bosch Dishwasher E27 Error Code — Water Softener / Salt Regeneration Error

Q: Can I still use my dishwasher when E27 is showing?

Yes — E27 does not halt the wash cycle. The dishwasher will continue to run. However, without effective water softening, limescale will gradually build up on dishes and internal components. Refill the salt as soon as possible.

Q: How often does a Bosch dishwasher need salt?

Salt consumption depends on local water hardness and usage frequency. In a hard-water area like greater Boston, most households refill the reservoir every 4 to 8 weeks with daily use. The salt indicator light alerts you when the level is low.

Q: My reservoir is full — why is E27 still showing?

Three common reasons: the salt has bridged and formed a crust blocking brine flow; the reservoir cap is loose or its O-ring seal is damaged diluting the brine; or the regeneration solenoid valve has failed and is not opening to allow brine through. Work through the salt bridge and cap checks before booking a technician.

Tech — Needs Inspection Also shown as: E 27 27

Quick Answer

The E27 error code means the dishwasher's built-in water softener failed to complete its salt regeneration cycle correctly. In most cases this is a straightforward fix: the salt reservoir is empty or the salt has bridged (clumped), the salt filler cap is loose, or the regeneration valve has become stuck. Refilling the salt and performing a hard reset clears E27 in the majority of cases. If the code persists after the salt is confirmed full, the regeneration solenoid valve needs professional inspection.

Time

10–20 min

Difficulty

Easy

Tools

None needed

DIY Cost

$5–$15

What the E27 Code Means

Most Bosch dishwashers sold in North America include a built-in water softener — an ion-exchange resin tank that removes calcium and magnesium from the incoming water to prevent limescale buildup on dishes, the heating element, and the spray arms. The resin periodically needs to be recharged using dishwasher salt (coarse sodium chloride), a process called regeneration.

Regeneration starts

At the end of a cycle, the control board opens the regeneration valve to flush the resin tank with salt-saturated brine from the salt reservoir.

Brine flushes resin

The brine displaces the mineral ions captured in the resin, restoring its softening capacity. Spent brine is flushed to drain.

E27 if it fails

If the control board detects that regeneration did not complete — no salt available, valve stuck, or sensor fault — it logs E27 and alerts you.

The code is a protective alert, not an emergency. The dishwasher will usually still run cycles when E27 is displayed, but without effective water softening, limescale will gradually build up inside the machine and on your dishes. Addressing it promptly protects the long-term health of the appliance.

Note: E27 only appears on Bosch models that have a built-in water softener with a dedicated salt reservoir — typically the 300, 500, 800, and Benchmark series. If your model does not have a salt cap on the floor of the tub, this code applies to a different internal sensor fault.

Common Causes — Most Likely First

Salt reservoir is empty or nearly empty. The most common cause by far. The salt indicator light may already be on. Without salt, regeneration cannot produce brine and the cycle fails. Very common

Salt has bridged (clumped) in the reservoir. Old or damp salt forms a solid crust over the top of the reservoir, blocking brine flow even when salt is physically present below. The reservoir feels heavy but regeneration still fails. Common

Loose or improperly seated salt cap. The screw cap on the salt reservoir has not been tightened fully, allowing water to dilute the brine to below effective concentration. Common

Wrong type of salt used. Table salt, pool salt, or water conditioner pellets were used instead of coarse dishwasher salt. Fine salt clumps and can damage the resin; non-sodium additives in table salt foul the softener. Occasional

Regeneration solenoid valve stuck or failed. The valve that opens to allow brine flow during regeneration has seized in the closed position or burned out. Brine cannot enter the resin tank regardless of salt level. Less common — needs technician

Salt level sensor or flow sensor fault. The sensor that monitors salt concentration or brine flow is giving an incorrect reading, triggering E27 even when the system is functioning normally. Less common — needs technician

How to Fix the E27 Error — Step by Step

Locate the salt reservoir on the floor of the tub

Open the dishwasher door and look at the bottom of the tub. The salt reservoir is the round screw cap — usually labeled with a salt shaker icon — set into the floor, typically on the left side. Have a towel ready as opening the cap may release a small amount of water.

Check the salt level and top up if needed

Unscrew the cap counter-clockwise. Look inside with a flashlight — you should be able to see the salt filling the reservoir. If the reservoir is empty or less than half full, fill it with coarse dishwasher salt only (not table salt, rock salt, or water softener pellets). Use the funnel that came with the machine, or a standard kitchen funnel. Fill until salt is visible at the top — typically 1–1.5 kg. Replace the cap firmly and wipe away any spilled salt from the tub floor.

Important: Always use dedicated dishwasher salt — coarse sodium chloride with no additives. Brands like Finish, Cascade, or Somat dishwasher salt are all suitable. Table salt is too fine and contains anti-caking agents that damage the resin over time.

Break up any salt bridge

If the reservoir feels heavy when you tilt the machine but appears empty at the top, salt has bridged — it has formed a solid crust that leaves an air gap below. Insert a long wooden spoon or the handle of a spatula and stir firmly to break up the crust. You should feel salt granules underneath. Add fresh salt on top once the bridge is broken.

Check and tighten the salt cap

Screw the cap back on and tighten it firmly by hand — it should feel snug with no wobble. Do not overtighten. A loose cap allows wash water to continuously dilute the brine in the reservoir, preventing effective regeneration even with a full salt supply.

Check the cap seal: Inspect the rubber O-ring on the underside of the cap. If it is cracked, flattened, or missing, water will bypass the cap regardless of how tightly it is screwed. Replacement caps cost $5–$10 and are available for all Bosch models.

Run a full cycle immediately after refilling

Run a complete wash cycle — not a quick rinse. The first full cycle after refilling the salt reservoir triggers the regeneration process and gives the system a chance to clear the E27 fault. Do not expect the code to disappear before the cycle starts; it should clear during or after the first full cycle.

If E27 persists after a full cycle — hard reset

If the code remains after a full cycle with confirmed salt in the reservoir, perform a hard reset: unplug the dishwasher for 60 seconds, then plug back in and run another full cycle. This forces the control board to re-evaluate the softener system from scratch.

If E27 still returns — book a technician

If E27 reappears after the reservoir is confirmed full, the cap is tight, and a hard reset has been performed, the regeneration solenoid valve or salt sensor has failed. Both require professional diagnosis and replacement.

When to Call a Technician

E27 is resolved with a salt refill in the majority of cases. Book professional service if:

E27 returns after confirming the reservoir is full of correct-type salt and the cap is firmly sealed
E27 persists after a hard reset and a full wash cycle
The salt indicator light does not go out even immediately after filling the reservoir
You notice white mineral deposits building up on dishes or the tub interior despite a full salt reservoir — the softener is not functioning
You can hear the regeneration valve failing to click or hum at the end of a cycle (audible on quiet models)

Repair Cost Expectations

Salt Refill (DIY)

$5–$15

A 2 kg bag of Finish or Somat dishwasher salt costs $5–$10 at most grocery or hardware stores. This resolves E27 in the majority of cases.

Regeneration Valve Replacement

$140–$240

Typical Boston-area cost if the regeneration solenoid valve has failed — parts and labor. Salt level sensor replacement falls in a similar range.

Salt Full but E27 Won't Clear? We Can Help.

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Book Bosch Dishwasher Repair Call (781) 666-9565

Frequently Asked Questions

Can I still use my dishwasher when E27 is showing?

Yes — E27 does not halt the wash cycle the way a drainage or leak error does. The dishwasher will continue to run. However, without effective water softening, hard water minerals will gradually build up on dishes, glassware, the heating element, and the spray arms. Leaving E27 unaddressed for weeks accelerates limescale buildup and can shorten the life of internal components. Refill the salt as soon as possible.

What kind of salt should I use in a Bosch dishwasher?

Use coarse dishwasher salt — pure sodium chloride with no additives, anti-caking agents, or iodine. Brands like Finish, Somat, or Cascade dishwasher salt are all appropriate. Do not use table salt (too fine, contains additives), rock salt (inconsistent purity), pool salt (may contain stabilizers), or water softener pellets (wrong size and composition). Only coarse dishwasher salt is safe for the ion-exchange resin inside the softener.

How often does a Bosch dishwasher need salt?

Salt consumption depends on your local water hardness and how frequently you run the machine. In a hard-water area (common in greater Boston), most households refill the salt reservoir every 4–8 weeks with regular daily use. The salt indicator light on the door or display tells you when the level is low — don't wait for E27 to appear before refilling.

My reservoir is full — why is E27 still showing?

Three common reasons: the salt has bridged (formed a crust, blocking brine flow despite the weight), the reservoir cap is loose or its O-ring seal is damaged (diluting the brine), or the regeneration solenoid valve has failed and is not opening to allow brine through. Work through steps 3 and 4 of the fix guide above before booking a technician.

Does my Bosch dishwasher have a water softener?

Most Bosch dishwashers sold in North America — 300, 500, 800, and Benchmark series — include a built-in water softener with a dedicated salt reservoir. You can confirm this by opening the dishwasher and looking for a round screw cap (with a salt or grain icon) on the floor of the tub. Entry-level models (100 Series) may not include this feature, in which case E27 would relate to a different internal sensor and a technician should diagnose it.