Biasi Parva 24S Fault codes & diagnostics

10 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

System Natural Gas 24 kW Discontinued

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10 High
Just want the most common Biasi Parva 24S faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 10 documented codes

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30c

Your boiler has likely detected a problem with the temperature sensor or its wiring, meaning it cannot accurately gauge how hot the water is.

High Engineer only £90-160

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring Harness
  • Main PCB
Full explanation for 30c
ER + 14 + Reset

Your boiler has detected an internal communication error or a control board failure that prevents it from starting up safely.

High Engineer only £180-350

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness
Full explanation for ER + 14 + Reset
ER + 25 + Reset

Your boiler has likely detected a circulation or temperature sensing issue, meaning the water is either not moving correctly or the boiler thinks it is overheating.

High DIY-safe £120-350

What to check first

  1. Check that the boiler pressure is between 1.0 and 1.5 bar
  2. Ensure all radiator valves and isolation valves under the boiler are fully open
  3. Try bleeding your radiators to remove any trapped air
  4. Press and hold the Reset button for 5 seconds

Parts commonly replaced

  • Circulation Pump
  • Main Heat Exchanger
  • NTC Temperature Sensor
Full explanation for ER + 25 + Reset
ER + 69

Your boiler has detected an electrical configuration error and cannot operate safely, meaning you will have no heating or hot water until it is reset or repaired.

High DIY-safe £100-280

What to check first

  1. Locate the selector switch on the front control panel
  2. Turn the dial to the 'R' (Reset) position for five seconds
  3. Turn the dial back to the 'On' position and wait for the boiler to restart

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • External Interface Connection
Full explanation for ER + 69
ER 01 + Reset

Your boiler has failed to light the flame or has lost it during operation, causing the system to lock out for safety.

High DIY-safe £120-350

What to check first

  1. Check that your gas supply is turned on and other gas appliances are working.
  2. Press and hold the 'Reset' button for five seconds to see if the boiler restarts.
  3. If it has been very cold, check that the white plastic condensate pipe outside hasn't frozen.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Printed Circuit Board (PCB)
Full explanation for ER 01 + Reset
ER 02 + Reset

Your boiler has likely overheated, causing a safety cutout to stop the system from running.

High DIY-safe £100-280

What to check first

  1. Turn the selector switch to the 'Reset' position for a few seconds, then back to the 'On' position.
  2. Check that your radiator valves are open and not turned off.
  3. Ensure your boiler pressure is between 1 and 1.5 bar on the pressure gauge.

Parts commonly replaced

  • Overheat Thermostat
  • Pump
  • Main Heat Exchanger
Full explanation for ER 02 + Reset
ER 03 + Reset

Your boiler has detected a problem with how it disposes of waste gases or brings in fresh air, causing it to shut down for safety.

High DIY-safe £100-280

What to check first

  1. Check the outdoor flue pipe for any obvious obstructions like bird nests, leaves, or debris.
  2. If it is freezing outside, check if the white plastic condensate pipe is blocked with ice.
  3. Press and hold the reset button for 5 seconds to see if the error clears.

Parts commonly replaced

  • Air Pressure Switch
  • Fan
  • Venturi Tube
Full explanation for ER 03 + Reset
ER 10 + reset

Your boiler has detected that the water pressure is too low, causing the system to shut down for safety.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (braided silver hose) underneath the boiler
  2. Slowly open both taps/valves until you hear water entering the system
  3. Close both valves once the pressure gauge on the front reaches between 1.0 and 1.5 bar
  4. Press the Reset button

Parts commonly replaced

  • Filling loop
  • Water pressure switch
  • Expansion vessel
Full explanation for ER 10 + reset
Li

Your boiler has detected that the water inside is getting too hot and has shut down as a safety precaution.

High DIY-safe £120-250

What to check first

  1. Check that all radiator valves are fully open to allow water to flow.
  2. Ensure the boiler pressure gauge is between 1.0 and 1.5 bar.
  3. Try resetting the boiler by turning the selector knob to the 'R' position for a few seconds.

Parts commonly replaced

  • Circulation Pump
  • Overheat Thermostat
  • Temperature Sensor (NTC)
Full explanation for Li
LP

Your boiler has detected that the water pressure is too low, causing it to stop running to prevent damage.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath your boiler.
  2. Slowly open the small valves on the hose until you hear water flowing.
  3. Watch the pressure gauge and close the valves when the needle reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure sensor
Full explanation for LP