A71
Buderus
Solar or Auxiliary Temperature Sensor Fault (if connected)
Error A71 is displayed; heater may run at reduced output or shut down.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Open or shorted solar collector sensor, Faulty buffer tank sensor, Incorrect wiring to auxiliary sensor terminals, Sensor not configured correctly in control parameters
How to Fix / Troubleshooting
Safety: Turn off power before working on low-voltage sensor wiring.
- Confirm system configuration: Check whether a solar collector or auxiliary tank sensor is actually installed and enabled in the Buderus control settings.
- Inspect sensor location: For solar systems, locate the collector sensor on the roof or near the solar array. For buffer tanks, locate the sensor in the tank well.
- Check wiring: Follow the cable from the sensor back to the heater. Look for damage, loose connections, or water ingress at junction boxes.
- Measure resistance: Disconnect the sensor at the heater and measure resistance. Compare to Buderus NTC charts. Replace if out of range.
- Verify control settings: In the installer menu, confirm that the correct sensor type and function are selected. Disable unused sensors if the system does not include them.
- Restore power and test: Turn power back on and verify that the A71 code clears and that solar/auxiliary functions operate correctly.
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Repair Difficulty
Medium
3/5
Required Part
Solar Collector Sensor / Buffer Tank Sensor
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