Does this guide apply to your appliance?

Match the brand, device type and complete display code. The same code can mean something different on another product family or market; a series name does not confirm every model in that series.

No exact model number is recorded here. Confirm the code in your appliance manual before following a check.

Likely causes

  • Limescale accumulation in the dishwasher heating system due to hard water.
  • Insufficient use of descaling agents leading to mineral deposits.
  • Lack of dishwasher salt in dishwashers equipped with water softeners.
  • Regular use without maintenance resulting in buildup over time.

What to try

Descale the Dishwasher to Remove Limescale

Easy
  1. Purchase a suitable dishwasher descaling product such as Bosch Quick Descaler (part number 00311506) or Dishwasher Care (part number 00311565).
  2. Ensure the dishwasher is empty before starting the process.
  3. Follow the instructions provided with the descaling product carefully.
  4. Run a full cleaning cycle using the descaler according to manufacturer's directions.
  5. After the cycle, check if the E12 error has cleared.

Source for this check: www.bosch-home.com

Regularly Add Dishwasher Salt if Equipped with Water Softener

Easy
  1. Locate the salt compartment in your dishwasher (consult your user manual).
  2. Purchase dishwasher-specific softening salt if running low.
  3. Open the salt compartment and add the salt carefully without spilling.
  4. Close the compartment securely.
  5. Regularly replenish salt to prevent limescale formation.

Source for this check: www.bosch-home.com

Contact Bosch Customer Support for Recurring or Persistent Issues

Professional

This is a service referral, not a do-it-yourself repair procedure.

  1. If descaling and salt addition do not resolve the E12 error, or if it appears frequently, do not attempt internal repairs yourself.
  2. Prepare your dishwasher model number and error details.
  3. Call Bosch Customer Support at 1-800-944-2904 to arrange professional diagnosis and repair.
  4. Follow their guidance for authorized service or parts replacement if needed.

This step is marked professional. Stop if you are not qualified to continue.

Source for this check: www.bosch-home.com

The code returned or the check did not help?

Avoid repeated resets and do not select a replacement part from the code alone. Record the exact code, full model number, when it appeared, and the checks you tried with their results. Share these details with the manufacturer or service technician.

Disconnecting power does not establish that internal components are safe to touch. This guide does not authorize opening electrical components or bypassing safety devices.

Related error codes

Bosch E09Troubleshooting Bosch Dishwasher Error Code E09 (Heating Circuit Failure) Bosch E14Bosch Dishwasher Error Code E14: Water Inflow/Flow Meter Issue Bosch E15Troubleshooting Bosch Dishwasher Error Code E15 Bosch E16Troubleshooting Bosch Dishwasher Error Code E16 Bosch E17Troubleshooting Bosch Dishwasher Error Code E17 Bosch E18Bosch Dishwasher E18: Insufficient Water Flow

Useful guides

Water left in the dishwasher: safe checks and when to call for serviceA small amount of clean water near the filter may be normal. Water across the tub floor, dirty standing water,... Dishwasher Not Drying? Check Settings, Loading, and Safe MaintenanceUse these owner-safe checks to improve drying, understand what moisture is normal, and know when to call a tec... Dishwasher Filter Care: What You Can Clean—and When to Call a TechnicianLearn how to identify a removable dishwasher filter, clean it safely, and recognize when a pump problem needs...

References