As an expert in the UK boiler sector with decades of experience, I’ve decoded countless Vaillant boiler error codes that pop up on ecoTEC and atmoTEC models, often turning a cosy evening into a chilly puzzle.
If you’re facing one of these faults flashing on your display, it’s your boiler’s way of highlighting a problem before it worsens—whether it’s low pressure or a sensor glitch—and in this detailed walkthrough, I’ll cover the most frequent ones with simple explanations, root causes, and step-by-step remedies to empower you to act confidently.
What Are Common Vaillant Boiler Error Codes?
Common Vaillant boiler error codes are diagnostic signals that pinpoint specific issues in your heating system, from circulation problems to electrical faults, helping you or a professional resolve them swiftly.
These codes often stem from everyday wear or maintenance oversights; let’s delve into the top ones below, including what they signify, their triggers, and practical solutions.
F22 Error Code
The F22 error code on your Vaillant boiler indicates low water pressure in the system, triggering a safety lockout to prevent damage from inadequate circulation. This is a frequent alert in UK homes where gradual leaks or evaporation drop levels below the optimal 1-1.5 bar range.
Low Water Pressure
Low water pressure arises when the system’s fluid level dips too low, often from minor leaks in pipes, radiators, or valves, or natural evaporation in unsealed setups.
How to Fix Low Water Pressure
- Check the pressure gauge on your boiler—if it’s below 1 bar, locate the filling loop (usually braided hoses underneath).
- Slowly open the valves to add water until the gauge reads 1.2-1.5 bar, ensuring the system is cold to avoid inaccuracies.
- Close the valves tightly and reset the boiler; monitor for drops over days to spot leaks.
- If pressure falls repeatedly, inspect visible pipes and radiators for drips, then call a Gas Safe engineer for hidden issues.
Faulty Water Pressure Sensor
A faulty water pressure sensor occurs when the device misreads levels due to debris buildup, wiring faults, or internal failure, falsely signalling low pressure even when it’s fine.
How to Fix Faulty Water Pressure Sensor
- Reset the boiler to clear temporary glitches—hold the reset button for 5-10 seconds.
- Verify actual pressure with an external gauge if possible; if it matches but code persists, suspect the sensor.
- Contact a Gas Safe professional to test and clean or replace the sensor, costing around £100-£200 including labour.
Pump or Wiring Issues
Pump or wiring issues develop from loose connections, corrosion, or pump wear, interrupting the signal that confirms proper pressure.
How to Fix Pump or Wiring Issues
- Ensure all external valves are open and reset the boiler.
- Listen for pump noise—if absent or irregular, check power supply.
- A Gas Safe engineer must inspect and repair wiring or replace the pump, typically £150-£300.
F28 Error Code
The F28 error code signifies an ignition failure during startup, where the boiler can’t establish a flame after attempts, often locking out for safety. In my encounters, this hits during cold snaps when gas flow falters.
Insufficient Gas Supply
Insufficient gas supply happens when pressure is low, valves are closed, or the meter lacks credit in prepay systems, preventing fuel from reaching the burner.
How to Fix Insufficient Gas Supply
- Confirm other gas appliances work; if not, check your meter for credit and top up if needed.
- Ensure the boiler’s isolation valve is fully open.
- Reset the boiler; if unresolved, contact your gas supplier for pressure checks.
- For ongoing issues, a Gas Safe engineer can assess pipework.
Blocked Condensate Pipe
A blocked condensate pipe builds from frozen wastewater or debris, backing up and halting ignition to avoid unsafe operation.
How to Fix Blocked Condensate Pipe
- Locate the external pipe and thaw with warm water if frozen (common in UK winters).
- Clear visible blockages gently.
- Insulate the pipe with foam lagging to prevent repeats.
- If internal, summon a Gas Safe pro for flushing.
Faulty Ignition Components
Faulty ignition components like electrodes or leads degrade from corrosion or damage, failing to spark the gas.
How to Fix Faulty Ignition Components
- Reset the boiler to test.
- A Gas Safe engineer will clean or replace electrodes/leads, around £100-£200.
F29 Error Code
The F29 error code points to a flame loss during operation, where the burner ignites but then fails, causing a relight attempt that doesn’t succeed. From my perspective, recirculation of flue gases often plays a role in poorly ventilated setups.
Interrupted Gas Supply
Interrupted gas supply stems from temporary dips, like during peak demand or faulty regulators, extinguishing the flame mid-cycle.
How to Fix Interrupted Gas Supply
- Check for consistent gas to other devices.
- Reset and monitor.
- Involve your supplier for regulator inspection.
- Gas Safe check for valve issues.
Flue Blockage or Recirculation
Flue blockage or recirculation occurs from debris, nests, or poor installation allowing exhaust back in, destabilising the flame.
How to Fix Flue Blockage or Recirculation
- Inspect external flue for obstructions and clear.
- Reset boiler.
- Professional flue sweep or repositioning by Gas Safe engineer.
Condensate Drain Blockage
Condensate drain blockage from sludge or ice restricts wastewater exit, leading to pressure imbalances that snuff the flame.
How to Fix Condensate Drain Blockage
- Flush drain with warm water.
- Add insulation.
- Engineer for deep clean if needed.
F61 Error Code
The F61 error code denotes a gas valve actuation fault, where the valve doesn’t respond correctly to open or regulate fuel flow. This electrical glitch is common in older Vaillant models I’ve serviced.
Defective Gas Valve
A defective gas valve fails mechanically or electrically, often from wear or solenoid burnout.
How to Fix Defective Gas Valve
- Reset to confirm.
- Gas Safe test resistance and replace, £200-£400.
Wiring or Connection Faults
Wiring or connection faults arise from loose plugs or corroded cables interrupting signals to the valve.
How to Fix Wiring or Connection Faults
- Reset boiler.
- Engineer inspects and repairs harness.
PCB Defect
PCB defect involves the control board sending erroneous commands due to surges or age.
How to Fix PCB Defect
- Power cycle and reset.
- Replace PCB via Gas Safe, £300-£600.
F62 Error Code
The F62 error code indicates a gas valve switch-off delay, where the valve doesn’t close promptly after flame extinction, posing a safety risk. In rentals I’ve managed, this signals impending valve failure.
Delayed Valve Shutdown
Delayed valve shutdown from sticky mechanisms or electrical lag allows gas linger.
How to Fix Delayed Valve Shutdown
- Reset.
- Tightness test by engineer; replace valve.
PCB or Sensor Issue
PCB or sensor issue misinterprets flame signals, delaying closure.
How to Fix PCB or Sensor Issue
- Reset.
- Diagnose and replace faulty board/sensor.
F64 Error Code
The F64 error code highlights an electronics or NTC fault, where flow/return sensors or PCB give inconsistent readings. Moisture in UK damp homes often exacerbates this.
Short Circuit in NTC Sensors
Short circuit in NTC sensors from wiring damage or water ingress skews temperature data.
How to Fix Short Circuit in NTC Sensors
- Reset.
- Engineer checks and replaces sensors/wiring.
PCB Malfunction
PCB malfunction corrupts signal processing.
How to Fix PCB Malfunction
- Reset.
- Replace PCB.
F75 Error Code
The F75 error code means no pressure change detected when the pump starts, suggesting circulation or sensor problems. Sludge in hard water areas is a big factor here.
Blocked or Faulty Pressure Sensor
Blocked or faulty pressure sensor clogs with debris, missing pump-induced spikes.
How to Fix Blocked or Faulty Pressure Sensor
- Reset.
- Clean or replace sensor via engineer.
Pump Failure
Pump failure from seizure or wear prevents flow.
How to Fix Pump Failure
- Listen for operation; reset.
- Replace pump.
System Sludge or Air
System sludge or air restricts movement.
How to Fix System Sludge or Air
- Bleed radiators.
- Power flush by pro.
When Should You Get a New Boiler Quote?
If recurring Vaillant boiler error codes like these persist despite fixes, or your unit’s over 10 years with inefficiency creeping in, it’s prime time to upgrade for reliable performance and lower bills.
A modern A-rated Vaillant or alternative can eradicate these glitches. Request a free new boiler quote today from Boilers 2 Go for energy-savvy options.
FAQs
How can regular maintenance prevent Vaillant boiler error codes?
Annual Gas Safe servicing spots early sensor wear or sludge, cutting error code risks by up to 50% in UK climates.
What warranty implications arise from ignoring Vaillant error codes?
Delaying fixes can void warranties if damage worsens; always log codes and service promptly to maintain coverage.
Are there smart apps for monitoring Vaillant error codes remotely?
Vaillant’s myVAILLANT app notifies of emerging codes, aiding landlords in proactive management across properties.
How do UK energy regulations affect Vaillant error code resolutions?
Post-2025 rules favour eco-fixes, with grants for upgrades if codes signal inefficiency.
Can weather patterns trigger specific Vaillant error codes?
Yes, freezes often spark F28/F29 from condensate issues, while humidity boosts F64 electrical faults—prep seasonally.
I’m Penny North, a home energy heating expert. My mission is to demystify new boilers and complex heating systems to help you achieve a warm, cosy home with lower energy bills and a smaller environmental footprint.