Vaillant Turbomax Plus 824/828E Fault codes & diagnostics

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

Combi Natural GasLPG 24-28 kW 2001-2006 Discontinued

Replaced by: ecoTEC plus 831

Download the Vaillant Turbomax Plus 824/828E manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 25 High
Just want the most common Vaillant Turbomax Plus 824/828E faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 26 documented codes

Tap any card for details

F 22

Your boiler has detected that the water pressure level inside the heating system has dropped too low to operate safely.

High DIY-safe £80-120

What to check first

  1. Locate the filling loop (a metal braided hose) underneath the boiler or near your pipes.
  2. Slowly open the valves on the filling loop to let mains water into the system until the pressure gauge on the front reads between 1.0 and 1.5 bar.
  3. Close both valves tightly to prevent over-pressurisation.

Parts commonly replaced

  • Pressure relief valve
  • Pressure sensor
  • Expansion vessel

Related codes

Full explanation for F 22
F.00

Your boiler has lost connection with its internal temperature sensor, meaning it cannot monitor heat levels and has shut down as a safety precaution.

High Engineer only £90-160

Parts commonly replaced

  • Flow NTC thermistor
  • NTC wiring harness
  • PCB

Related codes

Full explanation for F.00
F.01

Your boiler has stopped working because a sensor that monitors water temperature has lost its connection or stopped sending a signal.

High Engineer only £90-160

Parts commonly replaced

  • Flow NTC Thermistor
  • Sensor Wiring Harness

Related codes

Full explanation for F.01
F.10

Your boiler has detected a loose connection or a fault with the sensor that monitors the temperature of the water returning to the unit.

High Engineer only £90-180

Parts commonly replaced

  • NTC Return Sensor
  • Wiring harness
  • Main PCB

Related codes

Full explanation for F.10
F.11

Your boiler has detected a faulty electrical signal from the temperature sensor that monitors the water returning to the unit, meaning it cannot accurately judge when to heat your home.

High Engineer only £120-200

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness

Related codes

Full explanation for F.11
F.20

Your boiler has switched itself off because it has become too hot internally and needs time to cool down before it can be used again.

High DIY-safe £100-280

What to check first

  1. Check that all radiator valves are fully open to allow water to flow.
  2. Wait 30 minutes for the unit to cool down completely.
  3. Press the reset button (indicated by a flame with a cross through it) on the front control panel.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • NTC Sensor

Related codes

Full explanation for F.20
F.22

Your boiler has detected that there is not enough water pressure in the system to operate safely, causing it to shut down to prevent overheating.

High DIY-safe £0-180

What to check first

  1. Locate the silver braided filling loop hoses underneath or near the boiler.
  2. Open the two small valves on the filling loop to allow water into the system.
  3. Watch the pressure gauge on the front of the boiler until it reaches between 1.0 and 1.5 bar, then close both valves tightly.

Parts commonly replaced

  • Filling loop
  • Pressure sensor
  • Expansion vessel

Related codes

Full explanation for F.22
F.23

Your boiler has detected that it is not circulating water properly, which stops the system from heating up to prevent internal damage.

High Engineer only £120-250

Parts commonly replaced

  • Circulation pump
  • NTC sensors
  • Pump wiring harness

Related codes

Full explanation for F.23
F.24

Your boiler is struggling to move water around the system, often because the water level is too low or something is blocking the flow.

High DIY-safe £120-350

What to check first

  1. Check the pressure gauge on the front of the boiler; it should be between 1.0 and 1.5 bar.
  2. If the pressure is low, use the filling loop valves underneath the boiler to top it up.
  3. Ensure all radiator valves are fully open to allow water to flow freely.

Parts commonly replaced

  • Circulating pump
  • Pressure sensor
  • Heat exchanger

Related codes

Full explanation for F.24
F.27

Your boiler has detected an internal breakdown that is preventing it from starting up correctly, so it has shut itself down as a safety precaution.

High Engineer only £200-450

Parts commonly replaced

  • Main electronic PCB
  • Gas valve

Related codes

Full explanation for F.27
Showing 11–20 of 26
F.28

Your boiler is trying to start up but cannot light the gas flame required to provide heat or hot water.

High DIY-safe £100-280

What to check first

  1. Check that your gas emergency control valve is open and you have credit on your meter.
  2. Test another gas appliance, like a hob, to ensure gas is reaching the property.
  3. Press the 'Flame' or 'Reset' button on the boiler control panel for one second.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Ignition Lead
  • Spark Generator

Related codes

Full explanation for F.28
F.29

Your boiler was working but the flame has gone out unexpectedly, often due to an interrupted gas supply or a blockage in the drainage pipe.

High DIY-safe £100-£280

What to check first

  1. Check that your gas emergency control valve is open and you have credit on your meter.
  2. If it is freezing outside, check if the plastic condensate pipe leading outdoors is frozen and thaw it with warm water.
  3. Press the 'Flame/Cross' reset button for one second to see if the boiler restarts.

Parts commonly replaced

  • Ignition electrodes
  • Gas valve
  • Flame sensing electrode

Related codes

Full explanation for F.29
F.32

Your boiler has detected an issue with the fan that helps it vent safely, so it has stopped working to protect itself.

High Engineer only £150-250

Parts commonly replaced

  • Fan
  • Fan wiring harness

Related codes

Full explanation for F.32
F.33

Your boiler has stopped working because it cannot confirm that air is moving through the flue correctly, triggering a safety shut-down to prevent combustion issues.

High Engineer only £150-350

Parts commonly replaced

  • Air pressure switch
  • Fan unit
  • Venturi
  • Printed Circuit Board

Related codes

Full explanation for F.33
F.37

Your boiler has detected that the fan, which manages the air and gas mixture, is not spinning at the correct speed, causing the system to stop working for safety reasons.

High Engineer only £150-350

Parts commonly replaced

  • Air pressure switch
  • Fan assembly
  • PCB (Printed Circuit Board)

Related codes

Full explanation for F.37
F.41

Your boiler’s internal computer has lost its memory regarding the type of gas it should use, causing it to stop working for safety reasons.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

Full explanation for F.41
F.42

Your boiler is struggling to communicate with its internal components because of a damaged or loose wire inside the casing.

High Engineer only £150-250

Parts commonly replaced

  • Wiring harness
  • Cable loom
  • Printed Circuit Board connector

Related codes

Full explanation for F.42
F.43

Your boiler has detected an issue with its internal wiring connections, meaning it cannot communicate correctly between its own components and has safely shut down to prevent damage.

High Engineer only £150-250

Parts commonly replaced

  • Wiring loom
  • PCB (Printed Circuit Board)

Related codes

Full explanation for F.43
F.60

Your boiler has detected an internal electrical fault with the gas valve, which means it cannot safely light the flame to provide heating or hot water.

High Engineer only £250-£450

Parts commonly replaced

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

Related codes

Full explanation for F.60
F.61

Your boiler has detected an electrical communication problem with the gas valve, which means it cannot safely light the flame to provide heating or hot water.

High Engineer only £250-£550

Parts commonly replaced

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

Related codes

Full explanation for F.61
Showing 21–26 of 26
F.62

Your boiler has identified a safety issue where the gas valve remains open or is leaking gas when it should be shut off, causing it to lock out for protection.

Emergency Engineer only £250-450

Parts commonly replaced

  • Gas Valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for F.62
F.63

Your boiler's main computer brain is experiencing an internal electronic communication failure and has safely shut itself down to prevent further damage.

High Engineer only £250-450

Parts commonly replaced

  • Main printed circuit board (PCB)

Related codes

Full explanation for F.63
F.64

Your boiler has stopped working because its internal computer is receiving conflicting or faulty information from its temperature sensors.

High Engineer only £180-450

Parts commonly replaced

  • NTC Temperature Sensors
  • Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

Full explanation for F.64
F.65

Your boiler’s internal electronics have become too hot and have shut down to prevent damage to the control board.

High Engineer only £180-350

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Electronic Control Box

Related codes

Full explanation for F.65
F.66

Your boiler's control panel is having trouble communicating with its internal computer, which means the system has stopped working to prevent further damage.

High Engineer only £200-450

Parts commonly replaced

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

Related codes

Full explanation for F.66
F.67

Your boiler's main control board has detected a communication error with its flame sensing system, meaning it cannot safely confirm if the gas is lit.

High Engineer only £280-450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Ignition Electrode
  • Flame Sensing Electrode

Related codes

Full explanation for F.67
Status & diagnostic codes

66 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

d.00 Diagnostic Your boiler is currently operating in a reduced power mode as part of its normal diagnostic or configuration routine. d.01 Diagnostic Your boiler is currently running its internal water pump to safely move leftover heat away from the heating element, which is a normal part of the cooling-down process. d.02 Diagnostic Your boiler is simply taking a short, scheduled rest period between heating cycles to prevent unnecessary wear and tear. d.05 Diagnostic This code is simply showing you the current target temperature setting for your heating water rather than indicating a fault. d.07 Diagnostic Your boiler is simply reporting the current temperature setting of the 'warm start' feature, which keeps a small amount of water pre-heated for faster taps. d.08 Diagnostic This code simply indicates that your boiler is currently in standby mode because it hasn't been asked to provide any heating or hot water at this moment. d.10 Diagnostic This code is an information display confirming that your boiler's internal water pump is currently switched on and circulating water through your heating system. d.11 Diagnostic Your boiler is currently detecting that the water circulation pump responsible for moving heat around your home is switched off when it should be active. d.21 Diagnostic Your boiler is failing to detect the flame that it is trying to light, which prevents it from heating your home or water. D.22 Diagnostic Your boiler is currently performing an internal background system check and is not actually reporting a hardware malfunction. d.23 Diagnostic This code is not actually an error; it simply confirms whether your boiler is currently set to provide only hot water or both heating and hot water. D.24 Diagnostic Your boiler is currently performing a diagnostic check on its external controls, such as your room thermostat or timer, to ensure they are communicating correctly. d.25 Diagnostic This code simply indicates that your boiler's 'pre-heat' feature, which keeps water hot for faster delivery to your taps, is currently switched off. d.30 Diagnostic Your boiler is struggling to detect or control the flow of gas required to ignite the flame. d.33 Diagnostic Your boiler is struggling to confirm that the internal fan is spinning at the speed required to safely vent exhaust gases, causing the unit to stop working to protect you. d.34 Diagnostic Your boiler is struggling to confirm that its internal fan is spinning at the correct speed, which is preventing it from safely starting up. d.35 Diagnostic Your boiler is struggling to tell the difference between heating your home and heating your tap water, which may cause your radiators to get hot when you only want a shower. d.37 Diagnostic Your boiler is struggling to communicate with the internal valve that controls gas flow, which prevents it from igniting properly to heat your water or home. d.40 Diagnostic Your boiler is simply displaying the current temperature of the water flowing through the heating system, rather than indicating a fault. d.41 Diagnostic Your boiler is simply displaying a live temperature reading from its return pipe, which is a status update rather than an active fault code. d.50 Diagnostic Your boiler is simply displaying a status message indicating the current temperature of the water flowing through your heating system, rather than reporting an actual fault. d.60 Diagnostic Your boiler has detected that it has shut itself down due to overheating several times in the past, which suggests there may be a buildup of internal debris or an issue with water circulation. d.61 Diagnostic Your boiler has recorded several instances where it failed to start correctly and shut down as a safety precaution. d.64 Diagnostic This code is an internal status report showing how long your boiler takes to light the flame, rather than an active fault that stops the unit from working. d.65 Diagnostic Your boiler is failing to light because it cannot detect a flame within the required time, meaning you currently have no heating or hot water. d.67 Diagnostic Your boiler is currently in a temporary cooling-down phase and will restart automatically once a short safety delay has passed. d.68 Diagnostic Your boiler has failed to start up properly after several attempts and has now locked itself out for safety reasons. d.69 Diagnostic Your boiler has failed to start up properly after several attempts to light the gas burner. d.71 Diagnostic This code is simply a diagnostic setting that indicates the maximum temperature limit your boiler is allowed to reach when heating your home. d.72 Diagnostic This code is just an information message confirming that your boiler is circulating water for a few seconds to ensure hot water is ready when you turn on the tap. d.73 Diagnostic Your boiler is displaying a status code that indicates a internal calibration setting for the hot water pre-heat function has been adjusted from the factory default. d.75 Diagnostic Your boiler has reached its programmed limit for how long it can heat hot water continuously, which is likely just a setting notification rather than a breakdown. d.76 Diagnostic Your boiler's electronic settings do not match the type of gas being supplied to your home, preventing it from igniting safely. d.80 Diagnostic This code is simply an information display showing the total number of hours your boiler has been heating your home, rather than indicating a fault. d.81 Diagnostic This code is not a fault, but simply an information display showing the total number of hours your boiler has spent heating your hot water. d.82 Diagnostic This code is simply an information display showing the total number of times your boiler has started up since it was installed, rather than indicating a fault. d.83 Diagnostic This code is simply an information display showing how many times your hot water system has started up, rather than an indication of a fault or breakdown. S.00 Status Your boiler is currently in standby mode because it has not been asked to provide any heating. S.01 Status Your boiler is currently performing a normal startup routine where it clears the system before igniting, so it is likely functioning exactly as it should. S.02 Status Your boiler is simply preparing to start the heating process by circulating water, so this is a normal operational status rather than a fault. S.03 Status Your boiler is currently trying to light the gas flame to provide heating, so it is working normally and just going through its startup process. S.04 Status Your boiler is operating normally and has successfully turned on the flames to provide heat to your radiators. S.05 Status Your boiler is currently just finishing a normal cooling cycle, where it pushes heat away from the unit to protect its internal parts after being turned off. S.07 Status Your boiler is simply performing a routine safety cycle where it keeps the pump running for a short time to move leftover heat away from the system, and this is completely normal behavior. S.08 Status Your boiler is perfectly fine; it is currently in a brief, automatic rest period after just finishing a heating cycle to prevent overheating. S.10 Status Your boiler is currently operating normally as it is in the process of heating water for your taps or shower. S.11 Status Your boiler is currently just running its internal fan to prepare for heating your water, which is a normal part of its startup process. S.13 Status Your boiler is currently trying to light the flame to heat your water, but it has not yet confirmed that the flame has successfully started. S.14 Status Your boiler is currently operating normally as it heats water for your taps or shower. S.16 Status Your boiler is currently running its internal fan to clear out hot air after use, which is a normal part of the cooling process after you turn off a hot tap. S.17 Status Your boiler is currently cooling itself down after providing hot water, which is a normal part of its operating cycle. S.20 Status Your boiler is currently working correctly and is simply maintaining its internal temperature so that hot water is available to your taps instantly. S.21 Status Your boiler is simply performing a routine check of its internal fan before starting to provide hot water. S.23 Status Your boiler is currently going through its normal, safe process to ignite the flame for your hot water supply. S.24 Status Your boiler is currently operating normally to maintain the temperature of your hot water system for faster delivery. S.27 Status Your boiler is currently running its internal pump to move residual heat around the system after the hot water or heating has finished. S.28 Status Your boiler is perfectly fine; this isn't a fault but a protective waiting period designed to prevent the system from turning on and off too frequently. S.30 Status Your boiler is currently in standby mode because it is not receiving a signal from your thermostat or timer to turn on the heating. S.31 Status Your boiler is perfectly fine; it is simply set to 'summer mode' which means it will provide hot water when you turn on a tap, but will not heat your radiators. S.32 Status Your boiler has paused its operations because it detected a problem with the fan's speed, which triggers a safety feature to prevent the internal pipes from freezing. S.33 Status Your boiler has paused because it is struggling to breathe clearly, meaning it cannot pull in fresh air or push out exhaust fumes correctly. S.34 Status Your boiler is temporarily running its pump to prevent the water inside from freezing because the temperature around the pipes has dropped low. S.36 Status Your boiler is currently in standby mode because it is not receiving a signal from your thermostat to turn on the heating. S.39 Status Your boiler has detected that the water in your underfloor heating circuit has become too hot and has automatically shut down to prevent damage to your flooring. S.53 Status Your boiler is temporarily paused because it has detected that the water pressure inside the heating system is too low to run safely. S.54 Status Your boiler has temporarily entered a cooling-down pause because the water inside is heating up too quickly.