Vaillant ecoFIT Pure 830 Fault codes & diagnostics

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

Combi Natural Gas 30 kW 2016-present

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Each cell = one fault code. Hover to identify.
1 Emergency 36 High 5 Medium 10 Low

All 52 documented codes

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con

Your boiler has lost the ability for its internal computer brains to talk to each other, meaning it has shut down to prevent incorrect operation.

High Engineer only £200-450

Parts commonly replaced

  • Main PCB
  • Wiring harness
  • Display interface cable

Related codes

Connection

Your boiler's control panel has lost its connection to the main computer inside, meaning the system cannot receive instructions to provide heating or hot water.

High Engineer only £180-350

Parts commonly replaced

  • User interface display
  • Main printed circuit board (PCB)
  • Communication wiring harness

Related codes

d.14

Your boiler is notifying you that it needs to recalibrate how fast it moves water through your heating system to ensure your home warms up efficiently.

Low Engineer only £90-180

Parts commonly replaced

  • Pump
  • Printed Circuit Board

Related codes

F.00

Your boiler has lost its connection to the sensor that measures how hot the internal water is, so it has turned itself off as a precaution.

High Engineer only £150-250

Parts commonly replaced

  • NTC flow temperature sensor
  • Wiring harness

Related codes

F.01

Your boiler has lost the signal from one of its internal temperature sensors, causing it to stop heating to prevent potential damage.

High Engineer only £120-220

Parts commonly replaced

  • Return temperature sensor
  • Wiring harness

Related codes

F.10

Your boiler has stopped working because one of its internal temperature measurement sensors is malfunctioning or its wiring has disconnected.

High Engineer only £120-200

Parts commonly replaced

  • NTC Flow Temperature Sensor
  • Wiring harness

Related codes

F.11

Your boiler has detected an electrical fault with the internal sensor that monitors the temperature of the water returning to the system, causing it to shut down for safety.

High Engineer only £120-200

Parts commonly replaced

  • Return temperature sensor
  • Wiring harness

Related codes

Showing 11–20 of 52
F.12

Your boiler has lost the ability to read the temperature of the water in your hot water cylinder because there is an electrical fault with the sensor cable or the connection.

Medium Engineer only £120-220

Parts commonly replaced

  • Cylinder temperature sensor NTC
  • Wiring harness

Related codes

F.13

Your boiler has lost the ability to accurately measure the temperature of your hot water tap supply, which means it will stop heating it until the sensor is fixed.

Medium Engineer only £120-220

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Thermistor

Related codes

F.20

Your boiler has detected that it is getting too hot and has automatically shut down to prevent damage or overheating.

High Engineer only £120-250

Parts commonly replaced

  • NTC Thermistor
  • Pump
  • Heat Exchanger
  • PCB

Related codes

F.22

Your boiler has stopped working because the water level inside the system is too low to operate safely.

High DIY-safe £60-120

What to check first

  1. Locate the filling loop (a flexible silver hose) underneath your boiler, often found near the pipework connections.
  2. Open the valves on both ends of the loop to allow mains water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.
  3. Turn off both valves tightly to stop the flow of water and ensure the loop is not leaking.

Parts commonly replaced

  • Pressure Relief Valve (PRV)
  • Expansion Vessel
  • Pressure Sensor

Related codes

F.23

Your boiler has detected that the water inside it is heating up or moving much faster than expected, so it has shut itself down to prevent any damage.

High Engineer only £150-300

Parts commonly replaced

  • Pump
  • NTC sensors
  • Heat exchanger

Related codes

F.24

Your boiler has detected that the water temperature inside is rising far too quickly, so it has safely shut itself down to prevent damage.

High Engineer only £150-300

Parts commonly replaced

  • System pump
  • Pressure sensor
  • NTC thermistor

Related codes

F.25

Your boiler has detected that the exhaust gases are getting too hot and has automatically shut itself down to prevent any damage to the internal components.

High Engineer only £150-350

Parts commonly replaced

  • NTC temperature sensor
  • Heat exchanger
  • Flue gas thermostat

Related codes

F.27

Your boiler has detected a potential problem with the sensors that monitor the flame, leading it to shut down for safety reasons.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Flame detection electrode
  • Wiring harness

Related codes

F.28

Your boiler is failing to light the flame needed to produce heat and hot water.

High Engineer only £150-350

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

F.29

Your boiler has switched itself off because the flame inside went out unexpectedly while it was running.

High Engineer only £150-350

Parts commonly replaced

  • Gas valve
  • Ignition electrode
  • Flame rectification probe
  • PCB

Related codes

Showing 21–30 of 52
F.32

Your boiler has detected that the internal fan responsible for safely venting exhaust gases is not spinning, so it has shut down to prevent unsafe operation.

High Engineer only £200-350

Parts commonly replaced

  • Fan unit
  • Printed Circuit Board (PCB)
  • Wiring harness
F.49

Your boiler is having trouble communicating with its external controls, likely due to a loose wire or a problem with the connection between your thermostat and the boiler.

High Engineer only £120-250

Parts commonly replaced

  • eBUS wiring harness
  • PCB (Main Printed Circuit Board)
  • External thermostat

Related codes

F.61

Your boiler has detected an internal electrical issue that prevents it from safely controlling the gas supply, so it has shut down to protect your home.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Gas valve wiring harness

Related codes

F.62

Your boiler has detected that the gas valve is not closing correctly, so it has purposefully shut itself down to ensure your home remains safe.

Emergency Engineer only £200-350

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

F.63

Your boiler's computer memory has encountered a data corruption error, meaning it can no longer safely control the system's operation.

High Engineer only £250-400

Parts commonly replaced

  • Main printed circuit board (PCB)

Related codes

F.64

Your boiler's computer is detecting a communication error, meaning it cannot properly monitor its own internal systems to run safely.

High Engineer only £200-450

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Wiring harness

Related codes

F.65

Your boiler has detected that its internal safety computer is getting too hot and has stopped working to prevent damage.

High Engineer only £150-300

Parts commonly replaced

  • Main PCB
  • Wiring harness

Related codes

F.67

Your boiler has detected an issue with the internal sensor that monitors the flame, preventing it from safely starting up.

High Engineer only £180-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

F.68

Your boiler is struggling to keep the flame lit consistently, causing it to shut down for safety reasons.

High Engineer only £150-300

Parts commonly replaced

  • Flame rectification electrode
  • Ignition lead
  • PCB

Related codes

F.70

Your boiler's internal computer has forgotten its identity settings, preventing it from starting up correctly.

High Engineer only £150-300

Parts commonly replaced

  • Main printed circuit board (PCB)
  • Display interface module

Related codes

Showing 31–40 of 52
F.71

Your boiler has stopped heating because it is unable to accurately measure the temperature of the water flowing through it, so it has shut down as a safety precaution.

High Engineer only £150-250

Parts commonly replaced

  • Flow temperature sensor
  • NTC thermistor

Related codes

F.72

Your boiler has detected that the water temperature readings at the entry and exit points are not matching up correctly, which has caused it to shut down for safety.

High Engineer only £150-250

Parts commonly replaced

  • Flow/return temperature sensors
  • NTC thermistor
  • Main circuit board

Related codes

F.73

Your boiler is unable to read the water pressure correctly, which is preventing it from firing up safely.

High Engineer only £150-250

Parts commonly replaced

  • Pressure sensor
  • Wiring harness

Related codes

F.74

Your boiler's water pressure sensor is reporting an electrical reading that is outside of the expected range, which is preventing the system from operating safely.

High Engineer only £180-350

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness

Related codes

F.75

Your boiler is struggling to detect the movement of water, which usually means it cannot confirm the pump is working properly and has safely shut down to prevent damage.

High Engineer only £150-350

Parts commonly replaced

  • Pressure sensor
  • Central heating pump
  • Expansion vessel

Related codes

F.76

Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage to its internal parts.

High Engineer only £150-300

Parts commonly replaced

  • Primary heat exchanger
  • NTC temperature sensor
  • Pump

Related codes

F.77

Your boiler has detected an issue with how it clears waste water or exhaust gases, causing it to shut down for safety reasons.

High Engineer only £150-300

Parts commonly replaced

  • Condensate pump
  • Wiring harness
  • PCB

Related codes

F.78

Your boiler has lost communication with an external hot water control device, meaning it cannot properly manage your hot water temperature.

Medium Engineer only £120-250

Parts commonly replaced

  • DHW outlet sensor
  • Wiring harness
  • PCB

Related codes

F.83

Your boiler is struggling to detect a rise in water temperature, meaning it cannot confirm if the burners are effectively heating your home or water.

High Engineer only £150-250

Parts commonly replaced

  • NTC Temperature Sensor
  • Flow Sensor
  • Central Heating Pump

Related codes

F.84

Your boiler has detected that the water temperature is reading incorrectly, making it unsure if it is safe to heat your home.

High Engineer only £150-250

Parts commonly replaced

  • NTC temperature sensor
  • Wiring harness
  • Printed Circuit Board (PCB)

Related codes

Showing 41–50 of 52
F.85

Your boiler has detected that a temperature sensor is not sitting in the correct position, meaning it cannot accurately measure how hot the water is.

High Engineer only £120-220

Parts commonly replaced

  • Flow NTC sensor
  • Return NTC sensor
  • Sensor wiring harness

Related codes

F.86

Your boiler has lost the connection to your underfloor heating system, meaning it cannot properly communicate with or control the temperature of those specific rooms.

Medium Engineer only £120-250

Parts commonly replaced

  • External heating interface module
  • Wiring harness
  • Underfloor heating pump interface

Related codes

F.87

Your boiler is failing to detect a flame, which means it cannot light safely to provide you with heating or hot water.

High Engineer only £150-300

Parts commonly replaced

  • Ignition lead
  • Ignition electrode
  • Main PCB

Related codes

F.88

Your boiler has detected a problem with the internal mechanism that controls the gas supply, meaning it has safely shut itself down to prevent any unsafe operation.

High Engineer only £180-300

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

F.89

Your boiler has detected that the water pump responsible for circulating heat is not operating correctly, meaning your heating and hot water will not work.

High Engineer only £250-450

Parts commonly replaced

  • Central heating pump
  • Pump wiring harness
  • Printed Circuit Board

Related codes

F.91

Your boiler is having trouble reading the temperature of the water currently stored in your hot water cylinder because there is a faulty sensor or a damaged electrical connection.

Medium Engineer only £120-220

Parts commonly replaced

  • Cylinder NTC sensor
  • Wiring harness
P.00

Your boiler is currently running an automatic process to clear trapped air from its internal pipes to help it hum along smoothly.

Low DIY-safe

What to check first

  1. Wait for the process to complete, which typically takes a few minutes.
  2. Check that the small cap on top of the automatic air vent inside the boiler is unscrewed slightly to allow air to escape.
  3. Restart the boiler if the code remains visible after 15 minutes.

Parts commonly replaced

  • Automatic air vent

Related codes

P.01

Your boiler is currently performing a brief, automated internal health check by running at full power to ensure everything is operating correctly.

Low Engineer only
P.02

Your boiler is currently running a routine internal test to ensure it is burning fuel efficiently at its lowest power setting.

Low Engineer only
P.06

Your boiler is currently in a special maintenance mode used for filling or draining the system, so it is temporarily paused and not providing heating or hot water.

Low Engineer only
Showing 51–52 of 52
S.14

Your boiler is currently working exactly as it should and is simply heating water for your taps or shower.

Low Engineer only