Buderus Heat Pump Error Codes & Fix Guide
Buderus Heat Pump Error Codes & Fix Guide (Complete HVAC Expert Guide)
If your Buderus heat pump is showing an error code, it’s not just a fault—it’s a built-in diagnostic message designed to protect your system and guide troubleshooting. Whether you’re a homeowner, HVAC technician, or dealer, understanding these codes can help you diagnose problems faster, reduce downtime, and improve system performance.
This guide covers Buderus heat pump error codes, causes, fixes, and advanced HVAC troubleshooting methods.
About Buderus Heat Pumps
Buderus is a premium European heating brand and part of Bosch Thermotechnology. Buderus heat pumps (Logatherm series) are widely used for energy-efficient residential and commercial heating systems.
Popular models include:
- Logatherm WLW series
- Logatherm WPL series
- Logatherm WSW geothermal units
1. What Are Buderus Heat Pump Error Codes?
Buderus heat pumps use intelligent control systems (Logamatic controllers) that continuously monitor:
- Temperature sensors
- Refrigerant pressure
- Compressor performance
- Water circulation
- Electrical components
When a fault is detected, the system displays:
- Error Codes (E / F Codes) → System stops or limits operation
- Warning Codes (A Codes) → Advisory alerts
2. Types of Buderus Heat Pump Faults
Electrical Faults
- Voltage fluctuations
- PCB failure
- Relay damage
Sensor Faults
- Outdoor temperature sensor
- Flow/return sensor
Refrigerant Faults
- Low refrigerant
- High pressure
- Compressor overheating
Hydraulic Faults
- Low water pressure
- Pump failure
- Air in system
Communication Faults
- Indoor ↔ outdoor communication issue
- Controller malfunction
3. Complete Buderus Heat Pump Error Code List
Critical Error Codes
| Code | Description |
|---|---|
| E01 | Flow temperature sensor fault |
| E02 | Return temperature sensor fault |
| E03 | Outdoor sensor fault |
| E04 | Evaporator sensor fault |
| E05 | Condenser sensor fault |
| E06 | Discharge temperature fault |
| E07 | Defrost sensor fault |
| E08 | DHW sensor fault |
| E09 | Flow switch error |
| E10 | High pressure fault |
| E11 | Low pressure fault |
| E12 | Compressor overload |
| E13 | Expansion valve fault |
| E14 | Defrost failure |
| E15 | Freeze protection active |
| E16 | Pump failure |
| E17 | Communication error |
| E18 | Voltage fault |
| E19 | PCB fault |
| E20 | General system fault |
Warning Codes
| Code | Description |
|---|---|
| A01 | Temporary interruption |
| A02 | Defrost active |
| A03 | Compressor delay |
| A04 | Anti-freeze mode |
| A05 | System optimization |
4. Common Buderus Error Codes Explained
E10 – High Pressure Fault
Causes:
- Dirty condenser coil
- Blocked airflow
- Overcharged refrigerant
Fix:
- Clean outdoor unit
- Check fan motor
- Adjust refrigerant charge
E11 – Low Pressure Fault
Causes:
- Refrigerant leak
- Expansion valve blockage
Fix:
- Leak detection
- Recharge refrigerant
E09 – Flow Switch Error
Causes:
- Low water flow
- Blocked filter
Fix:
- Clean strainer
- Check pump
E12 – Compressor Overload
Causes:
- High pressure
- Electrical imbalance
Fix:
- Check compressor amps
- Inspect capacitor
E17 – Communication Error
Causes:
- Wiring issue
- PCB failure
Fix:
- Inspect connections
- Replace board
E16 – Pump Failure
Causes:
- Mechanical issue
- Electrical failure
Fix:
- Check voltage
- Replace pump
5. Advanced Troubleshooting Workflow
Step 1: Identify Error Code
Read from display or controller.
Step 2: Reset System
- Turn OFF power
- Wait 5 minutes
- Restart
Step 3: Basic Inspection
- Power supply
- Water pressure
- Filters
Step 4: Sensor Testing
- Measure resistance
- Compare with chart
Step 5: Refrigerant Diagnosis
- Check pressure gauges
- Inspect for leaks
6. Sensor Fault Diagnosis
Buderus systems use NTC sensors.
Common Issues:
- Open circuit
- Short circuit
Testing:
- Multimeter
- Temperature vs resistance
7. Refrigerant & Pressure Issues
Symptoms:
- Poor heating
- Ice formation
- Frequent shutdown
Causes:
- Gas leak
- Dirty evaporator
- Expansion valve issue
Fix:
- Leak repair
- Recharge system
- Clean coils
8. Electrical & PCB Faults
Common Codes:
- E17
- E18
- E19
Causes:
- Voltage fluctuation
- PCB damage
Fix:
- Install stabilizer
- Replace PCB
9. Communication Errors
Causes:
- Wiring faults
- Controller issues
Fix:
- Check cables
- Replace modules
10. How to Reset Buderus Heat Pump
Method 1:
Use reset button
Method 2:
Power OFF → Wait → ON
Method 3:
Reset via controller
11. Preventive Maintenance Checklist
Monthly:
- Check pressure
- Clean filters
Quarterly:
- Inspect wiring
- Test sensors
Yearly:
- Full servicing
- Refrigerant check
12. Pro HVAC Diagnostic Tips
Since you’re an HVAC professional, here are expert-level insights:
Superheat & Subcooling
- High superheat → low charge
- Low superheat → flooding
Delta T Monitoring
- Ideal: 5–10°C
Compressor Amp Check
- High amps → mechanical issue
Multi-Symptom Logic
- High pressure + low airflow → dirty condenser
- Low pressure + frost → refrigerant leak
13. FAQ Section
Q1. What does E10 mean on Buderus heat pump?
It indicates high refrigerant pressure due to airflow restriction or overcharging.
Q2. How do I reset a Buderus heat pump?
Turn off power, wait 5 minutes, and restart.
Q3. Why does low pressure error occur?
Due to refrigerant leaks or expansion valve faults.
Q4. Can I fix error codes myself?
Basic issues can be fixed, but complex faults require professionals.
Q5. How often should servicing be done?
At least once per year.
Final Thoughts
Buderus heat pumps are highly reliable systems backed by Bosch engineering. However, understanding error codes is essential for fast diagnosis, efficient repair, and long-term system performance.
This guide gives you a complete professional-level troubleshooting framework for Buderus heat pumps.
