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Vaillant Advance Partner · Gas Safe 599015 · Wokingham & RG40
Vaillant Boiler Fault Codes — Wokingham
ecoTEC Plus, Pro, Exclusive & ecoFIT — F.22, F.28, F.29, F.75, F.32 and more explained plainly
Your Vaillant boiler has locked out to protect itself. This guide covers every common fault code across the ecoTEC range — what each means, what you can safely try yourself, and when to call a Gas Safe engineer. Thermotec is Wokingham’s Vaillant Advance Partner, carrying genuine parts for a single-visit fix in most cases.
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Boiler showing a fault code?
Fixed price · Genuine Vaillant parts · Advance Partner
Diagnostic fee£96
First-time fix90%
ResponseSame day
Fault code index
Vaillant ecoTEC fault codes — full reference
Find your code below. Severity indicates whether you can try a fix yourself (Low) or whether a Gas Safe engineer is required (High/Medium). Do not keep resetting a High severity fault.
| Code | Fault | Common cause | Action | Severity |
|---|---|---|---|---|
| F.28 | Ignition failure | Gas supply issue, frozen condensate pipe (winter), faulty spark electrode | Check gas supply. Thaw condensate pipe if winter. Press Reset 3–5 sec. If it returns, engineer required. | High |
| F.29 | Flame loss during operation | Flue draught, low gas pressure, faulty ionisation sensor or gas valve | Press Reset once. If fault returns immediately, do not keep resetting — engineer diagnosis needed. | High |
| F.75 | Pump / pressure sensor fault | Pump seized or not detected; pressure sensor blocked with magnetite sludge | Check pressure is at 1.5 bar. Press Reset. If it returns, engineer needed — sensor replacement or powerflush likely required. | High |
| F.32 | Fan fault | Fan motor failure, flue blockage, wiring fault | Do not reset. Fan failure prevents safe venting of combustion gases. Gas Safe engineer required immediately. | High |
| F.27 | Flame without demand | Gas valve fault — flame present when boiler hasn’t called for heat | Turn off at wall. Do not restart. Safety-critical — Gas Safe engineer required before the boiler is used again. | High |
| F.22 | Low water pressure | Pressure below 0.5 bar — recently bled radiators, slow leak, failing expansion vessel | Repressurise to 1.5 bar using filling loop. If pressure keeps dropping, engineer needed to find leak. | Medium |
| F.73 | Pressure sensor fault (open circuit) | Faulty or disconnected pressure sensor | Check system pressure. If pressure is correct and fault persists, pressure sensor replacement required. | Medium |
| F.74 | Pressure sensor fault (short circuit) | Pressure sensor short circuit or wiring fault | Do not keep resetting. Wiring or sensor inspection needed by Gas Safe engineer. | Medium |
| F.0 | Central heating temperature sensor fault | Flow temperature sensor failure or wiring issue | Engineer inspection required. Boiler may operate in limited mode before shutdown. | Medium |
Stuart’s pro tip — the most common winter call-out in Wokingham
The F.28 caused by a frozen condensate pipe is the most common Vaillant fault we attend across RG40 in winter. The white or grey plastic condensate pipe exits the wall behind your boiler and can freeze solid overnight. Before calling an engineer, locate it and pour warm — not boiling — water along its length to thaw. Then press and hold the Reset button for 3–5 seconds. This resolves the fault at no cost in the majority of winter call-outs we attend in Wokingham, Woosehill, Finchampstead and surrounding villages.
Step-by-step fixes
Common Vaillant faults — what to try first
Work through these before calling. Some faults have a genuine DIY fix — others are clear signals to stop and call a Gas Safe engineer immediately.
F.28
Boiler fails to ignite
What it means
The boiler tried to light and failed. The most common winter cause in Wokingham is a frozen condensate pipe. Otherwise likely a gas supply issue or faulty ignition electrode.
Try this first
1
Check gas supply is live — confirm by trying a gas hob. Check meter credit if pre-pay.2
In winter: find the plastic condensate pipe exiting the wall. Pour warm (not boiling) water over it to thaw.3
Press and hold the Reset button (flame with cross symbol) for 3–5 seconds.If F.28 returns immediately — stop resetting. Book a diagnostic →
F.29
Flame lost during operation
What it means
The boiler ignited successfully but the flame cut out during operation. Often a gas pressure fluctuation, flue draught issue or a failing ionisation sensor or gas valve.
Try this first
1
Confirm gas supply is live on other appliances.2
Press Reset once for 3–5 seconds and observe whether the boiler fires and holds a flame.If F.29 returns on the next firing cycle, stop — gas valve or sensor fault. Book a repair →
F.22
Low water pressure
What it means
System pressure has dropped below 0.5 bar — the boiler has shut down to prevent the heat exchanger from overheating without sufficient water. Very common after bleeding radiators.
Try this first
1
Locate the filling loop — usually a silver braided hose with lever handles under the boiler.2
Slowly open the lever(s) until the pressure gauge reads 1.5 bar, then close fully.3
F.22 should clear automatically. If not, press Reset for 3–5 seconds.Topping up more than twice a year? Expansion vessel or hidden leak. Book a diagnostic →
F.75
Pump / pressure sensor fault
What it means
The boiler started the pump but didn’t detect a pressure rise — either the pump has seized after inactivity, or the pressure sensor is blocked with magnetite sludge. Very common in Wokingham’s hard water area.
Try this first
1
Check system pressure is at 1.5 bar — repressurise if needed.2
Press Reset once. If the boiler fires and runs, the fault may have been a temporary pressure spike.F.75 returning? Sensor or pump fault — we carry genuine Vaillant parts. Book a repair → · Consider a powerflush →
F.32
Fan fault
What it means
The fan is not running at the correct speed or at all. The fan vents combustion gases safely through the flue — without it working correctly, harmful gases including carbon monoxide could build up.
What to do
Do not reset. This is a safety lockout. A Gas Safe engineer must inspect the fan motor, capacitor and flue for obstructions before the boiler is restarted.
F.27
Flame without demand
What it means
Gas is detected burning inside the boiler when it hasn’t asked for heat. This is a gas valve fault and a safety-critical situation that must be treated seriously.
What to do
Turn the boiler off at the wall immediately. Do not restart it. Call a Gas Safe engineer. If you smell gas, call the National Gas Emergency line on 0800 111 999 first.
How to reset your Vaillant ecoTEC boiler
1
Look for the reset button — on most ecoTEC models it has a flame symbol with a cross through it, or is labelled ‘Reset’. On some models it is a dial you rotate.2
Press and hold the reset button for 3–5 seconds. The boiler will attempt to restart.3
Wait 2–3 minutes for the boiler to complete its startup sequence before checking if the fault code has cleared.If the same fault code appears immediately after a reset, stop. Repeated resets on a persistent fault can damage the PCB or burner. Call a Gas Safe engineer.
Common questions
Vaillant fault code FAQ
What’s the difference between F.28 and F.29?
F.28 means the boiler attempted to ignite and failed completely — no flame was established. F.29 means the flame was established but was then lost during operation. Both relate to gas or ignition faults. In winter, F.28 in Wokingham homes is most commonly caused by a frozen condensate pipe — thaw it with warm water and press Reset before calling an engineer.
Can I fix F.22 low pressure myself?
Yes, in most cases. Locate the filling loop under the boiler — a silver braided hose with one or two lever handles — and slowly open it until the pressure gauge reads 1.5 bar. Close the valves and press Reset. If your Vaillant boiler in Wokingham keeps losing pressure more than twice a year, you likely have a hidden leak or a failing expansion vessel that needs a professional inspection. Book a diagnostic.
Why is my Vaillant showing F.75?
F.75 means the boiler started the pump but didn’t detect the expected pressure rise — most commonly because the pressure sensor is blocked with magnetite sludge, or the pump has seized. Wokingham’s hard water makes this particularly common. Resetting may work temporarily but the root cause needs addressing. We carry genuine Vaillant pressure sensors on the van. A powerflush clears the sludge and a magnetic filter prevents it recurring.
Do you cover Woosehill, Finchampstead and Lower Earley?
Yes — we regularly attend properties in Woosehill, Finchampstead, Earley, Arborfield, Winnersh and Barkham. We cover the full RG40 and RG41 postcode area from our base in Arborfield.
How often should I service my Vaillant to prevent fault codes?
Annually. An annual Gas Safe service keeps your Vaillant warranty valid and is the single most effective way to prevent F.28, F.75 and F.22 faults. At a Thermotec Vaillant service we clean the burner, check the expansion vessel, inspect the pressure sensor and test flue gases — all the components most likely to cause lockouts. As a Vaillant Advance Partner we also issue the digital Benchmark record Vaillant requires for warranty claims.
My Vaillant is making a whistling sound — is it serious?
Kettling (a whistling or rumbling sound) is caused by limescale or sludge on the heat exchanger restricting water flow and causing local overheating. Not immediately dangerous but it will eventually crack the heat exchanger if left untreated — an expensive repair. A powerflush is the correct solution. Adding a magnetic filter prevents recurrence. Particularly common in Wokingham’s hard water area.
Coverage
Vaillant repair & servicing across Wokingham & Berkshire
Based in Arborfield — 10 minutes from Wokingham town centre. Covering the full RG40, RG41, RG2, RG5, RG6 and RG45 postcode area.
Related pages
More Vaillant & boiler support
Vaillant fault won’t clear? Call Stuart.
Vaillant Advance Partner · Gas Safe 599015 · £96 fixed diagnostic · 90% first-time fix · Genuine parts · Same-day where available · Wokingham & RG40