Bosch Dishwasher: heat pump problem

Professional Repair Guide

What is this symptom?

Experiencing issues with your Bosch dishwasher not heating water or drying dishes properly? This could indicate a malfunctioning heat pump, often accompanied by error codes like E31 or E09. Common causes include heat pump failure, faulty temperature sensors, or blockages. Understanding these issues can help you troubleshoot effectively.

Urgency: Medium

Important Tips for Bosch Models

  • Bosch error codes (e.g., E09, E12, E20, E21, E31) include specific mentions of heat pump faults, limescale build‑up, internal heater fault, and blocked heat pump as diagnostic cues.

Possible Causes

Heat pump failure or malfunction

How to Identify: Error codes related to heat pump (e.g., Bosch E09/E31/E21/E20, cold water at end of cycle, wet dishes, unusual noises from pump area.

Part: Heat pump assembly

Faulty temperature sensor (NTC) affecting heat pump operation

How to Identify: Dishwasher displays E31 or similar codes, multimeter continuity test of sensor out of spec, inconsistent temperature readings.

Part: Temperature sensor (NTC)

Blockage or limescale buildup within heat pump or related pathways

How to Identify: Bosch error codes like E12 indicate limescale build-up affecting heat pump and water heating; occurs in hard water areas.

Part: Heat pump internal pathways and limescale-prone components

Wiring or connection faults between heat pump, sensor, and control board

How to Identify: Intermittent operation, error codes, visible loose or damaged wires upon inspection.

Part: Wiring harness/electrical connections

Faulty control board misinterpreting heat pump signals

How to Identify: Error persists after replacing heat pump and sensor; visible damage on board, burnt smell.

Part: Main control board

DIY Solutions

Reset Dishwasher and Clear Temporary Errors

Easy 5–10 minutes
  1. Power off the dishwasher at the breaker or unplug.
  2. Wait 5–10 minutes for residual charge to dissipate.
  3. Restore power and run a short cycle to see if error clears.

Check and Clean Temperature Sensor and Connections

Moderate 30–60 minutes
Tools Needed: screwdriver, multimeter, soft cloth/vinegar
  1. Disconnect power and water supply.
  2. Remove bottom access panel and locate the NTC temperature sensor.
  3. Using a soft cloth with vinegar, gently clean around the sensor to remove scale.
  4. Use a multimeter to test sensor continuity.
  5. Reconnect and test operation.
⚠️ Safety First: Ensure power is off before accessing internal components.

Professional Repairs

Replace Heat Pump Assembly

Estimated Cost: $150–$400 for part, $200–$500 labor

Control Board Diagnosis and Replacement

Estimated Cost: $200–$600 for part, $300–$700 labor

When to Call a Professional

After DIY heat pump and sensor checks if error persists
Visible water leaks or burning smell
Uncertain electrical connections

Preventive Maintenance

  • Descale dishwasher with Bosch descaler: Limescale build‑up affecting heat pump and heating elements
    Frequency: every 3–6 months in hard water areas
  • Use recommended rinse aid and maintain filters: Reduced drying performance and heat transfer issues
    Frequency: Monthly

Frequently Asked Questions

Why is my Bosch Dishwasher heat pump problem?
Common causes include heat pump failure, faulty temperature sensors, and blockages.
How do I fix Bosch Dishwasher heat pump problem myself?
Try resetting the dishwasher or cleaning the temperature sensor for a DIY fix.
How much does it cost to fix heat pump problem?
Professional repairs range from $200 to $600, depending on parts and labor.
When should I call a technician for heat pump problem?
If DIY solutions don't resolve the issue, contact a technician for further diagnosis.

References & Sources

Community Analytical Insights

Analysis based on real user discussions from appliance repair communities

Can I Fix This Myself?

65%
DIY Success Rate Difficulty: Either

Common Issues Reported by Users

  • Faulty heat pump assembly
  • Blocked or clogged filters
  • Electrical issue (wiring or connections)

User Suggested Solutions

  1. Inspect and replace the heat pump assembly if faulty. Disconnect power, remove the bottom panel, and check the heat pump for signs of damage or wear. Replace if necessary.

  2. Clean or replace the filters. Remove the bottom panel, locate the filters, and clean them thoroughly. If damaged, replace them.

  3. Check electrical connections. Ensure all wiring to the heat pump is secure and free from corrosion. Repair any damaged wires.

Analysis based on 1 community discussions
View Sources

Data compiled from real discussions on r/appliancerepair and r/Appliances:

  1. Bosch Supersilence heat pump - how to access?

Community Discussions

E09 error indicating heat pump problem

Tilt the machine on its back or flip it upside down to access the heat pump by removing the bottom plastic panel.

DIY View on Reddit →

Source: Reddit r/appliancerepair

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