--- title: "Boiler Fault Finding & Diagnosis Scunthorpe | A T Plumbing & Heating" description: "Boiler error codes, no heat, no hot water, low pressure — diagnosed properly first. Covered across Scunthorpe, Hull, Grimsby and Doncaster. 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Covered across Scunthorpe, Hull, Grimsby and Doncaster. Mon–Fri 8am–5pm." }, { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "How much is a diagnostic call-out?", "acceptedAnswer": { "@type": "Answer", "text": "Flat fee of a small flat fee. That covers the diagnosis. Any repair you proceed with is quoted in writing on top — and the diagnostic fee is deducted from larger repairs over £300." } }, { "@type": "Question", "name": "How quickly can you attend?", "acceptedAnswer": { "@type": "Answer", "text": "Mon–Fri 8am–5pm across Scunthorpe, Brigg, Messingham, Scotter and Barton-upon-Humber. Mon–Fri 8am–5pm for Hull, Grimsby and Doncaster — earlier you call, better the slot." } }, { "@type": "Question", "name": "What if you can't fix it on the first visit?", "acceptedAnswer": { "@type": "Answer", "text": "If we need to order a specific part, we leave the system safe, give you a fixed-price quote, and return as soon as the part arrives. No charge for the second visit beyond the original fee and parts." } }, { "@type": "Question", "name": "Will you tell me if it's not worth fixing?", "acceptedAnswer": { "@type": "Answer", "text": "Yes — honestly. We'll show you the cost of repair vs the cost of replacement and the realistic remaining life. No commission, no upselling — your call." } }, { "@type": "Question", "name": "Do you cover oil-fired boilers?", "acceptedAnswer": { "@type": "Answer", "text": "No — we cover gas appliances only. We don't carry out oil-fired (OFTEC) work." } }, { "@type": "Question", "name": "Is my boiler too old to be worth repairing?", "acceptedAnswer": { "@type": "Answer", "text": "Generally we'd consider replacement once a boiler is 14+ years old, out of warranty, and needing £300+ of repair. Under that, repair usually wins. We'll lay out the numbers either way." } }, { "@type": "Question", "name": "Will my home insurance cover this?", "acceptedAnswer": { "@type": "Answer", "text": "Some home insurance policies cover unexpected breakdowns — we'll provide a written report and invoice that satisfies most insurers. Check your policy wording or ask us before we attend." } }, { "@type": "Question", "name": "Do you guarantee the repair?", "acceptedAnswer": { "@type": "Answer", "text": "12-month workmanship guarantee on every repair, in writing. Same fault returns, we come back free." } } ] } ] --- [info@atplumbing.co.uk ](mailto:info@atplumbing.co.uk)Winteringham, North Lincolnshire — covering Scunthorpe, Hull, Grimsby & surrounds Mon–Fri 8am–5pm · Family-run · Gas Safe registered 556262 [07576 593045 ](tel:07576593045) [![A T Plumbing & Heating (Lincs) Limited](/__l5e/assets-v1/4b011dd3-2dc4-4e91-b5f8-70b484305ad1/at-plumbing-heating-logo.png)](/) [Home](/)[About](/about) [Services](/services) [Service Areas](/service-areas) [Our Work](/our-work)[Reviews](/reviews)[Contact](/contact) [07576 593045 ](tel:07576593045)[Request Estimate](/contact) 1. [Home](/) 2. [Services](/services) 3. Fault Finding Boiler Fault Finding · Mon–Fri # Boiler error codes and heating faults diagnosed properly in Scunthorpe — before we quote, before we replace. We find the actual fault — not the part the previous engineer guessed at. Diagnosis booked Mon–Fri, fixed-price repair in writing, no replacement parts thrown at the problem hoping it sticks. [Request a Free Estimate](#enquiry) [07576 593045](tel:07576593045) ★★★★★ Diagnosis booked Mon–Fri · Repair quoted in writing before any work · 12-month workmanship guarantee. ## Get a Free Quote Tell us about the job — we'll reply fast with a no-obligation estimate. 18 years in plumbing & heating Gas Safe Registered — every gas job certified G3 Certified Unvented hot water qualified Mon–Fri 8am–5pm Fixed price Quote in writing before work starts Service overview ## Real diagnosis, not parts roulette The most expensive boiler repair is the one that didn't fix the problem. We see it constantly — a PCB swapped to fix what was actually a faulty sensor, a pump replaced to fix what was actually a stuck motorised valve. Every wrong part costs you, in money and in time without heat. We diagnose first. ### What it is Systematic fault diagnosis on combi, system and regular boilers — all major brands. Includes pressure testing, gas-rate verification, flue gas analysis, controls testing, motorised valve checks and sensor resistance measurement to isolate the real fault before quoting. ### Who it's for Homeowners and landlords across Scunthorpe, Brigg, Messingham, Scotter, Kirton Lindsey, Barton-upon-Humber, Hull, Grimsby and Doncaster whose boiler is throwing error codes, locking out, losing pressure, making noises or simply not delivering heat or hot water. ### When it's needed Boiler showing an error code (modern boilers all log their own fault codes); no heating; no hot water; intermittent operation; hot water but no heating; heating but no hot water; banging or kettling; pressure falling daily; or anything that's already had one failed repair. ### Why a professional matters Modern boilers have 15+ sensors and 20+ failure modes. Codes are signposts, not diagnoses. Replacing the part the code points to has a roughly 50% hit rate — proper diagnosis pushes that close to 100%, and that's the difference between one bill and three. What goes wrong ## Common faults — and what really causes them From thousands of call-outs across North Lincolnshire, here's what we actually find behind the symptom: ### Low pressure faults Usually a slow leak — most often the expansion vessel internal diaphragm, sometimes the PRV, occasionally a rad valve. Topping up daily masks it and corrodes the system. ### Pump pressure sensor faults Often the sensor itself; sometimes the pump; sometimes a blocked auto air vent. We test before we replace. ### Boiler firing then locking out Typically gas pressure, faulty ignition lead, or a flame-sense electrode that's carboned up. £30 part, often replaced as a £350 fan. ### Hot water cold after a few seconds Combi with a stuck diverter valve — well-known fault on Worcester Greenstar 30Si, fixable with a cartridge for ~£80 not a new valve at £280. ### Banging during heating cycles Air locks, sludge in the heat exchanger, or thermal shock from a stuck three-port valve. Three different causes, one symptom. ### Boiler 'works fine, then doesn't' after rain Almost always a condensate pipe freezing or kinking outside. Re-route internally and the call-outs stop. Our process ## Our fault-finding process Methodical — because the fault is rarely where the code points. 1. 01 ### History & Symptoms Quick conversation: when did it start, what's been done already, any patterns, any noises. Half the diagnosis. 2. 02 ### Visual & Pressure Boiler casing off, visual check, system pressure, gas working pressure and standing pressure all recorded. 3. 03 ### Code Read & Reset Fault log read (modern boilers store history), reset tested, behaviour observed under load. 4. 04 ### Component Testing Sensors tested by resistance, pump by current draw, valves by manual operation, flue gases analysed. Hard data before any part is swapped. 5. 05 ### Written Diagnosis & Quote Confirmed root cause, repair options and fixed price — in writing — before any parts are fitted. 6. 06 ### Repair, Test & Guarantee Repair carried out, system run under load to verify, 12-month workmanship guarantee logged in writing. Benefits ## Why diagnosis-first saves money ### Right fix, first time Methodical testing isolates the actual fault. Average call-out goes from 3 visits to 1. ### No wasted parts We don't replace anything we haven't proven faulty. You don't pay for guesses. ### Honest economic advice If your 14-year-old boiler is uneconomical to repair, we'll tell you with numbers — and quote the install fairly if you'd rather replace. ### Carry common parts PCBs are ordered; pumps, valves, sensors, ignition leads, expansion vessels live in the van. Often fixed on the first visit. ### Warranty preserved If your boiler is still under manufacturer warranty, we diagnose and then escalate to the right warranty engineer — without breaking the seal. ### 12-month guarantee On every repair we do. Same fault returns inside 12 months, the return visit is free. Recent work ## Real jobs, real installs. A few recent fault finding jobs completed across North Lincolnshire. ![Rusted, sludge-damaged boiler heat exchanger exposed during diagnostic fault finding](/__l5e/assets-v1/e17fdbd8-030f-4359-b3d0-c1617f3d178d/work-03.jpeg) ![Boiler combustion chamber inspection showing yellowed flue interior during fault diagnosis](/__l5e/assets-v1/c323e6ac-ec96-40bf-8584-869235cdf29a/work-04.jpeg) ![Close-up of boiler burner electrodes and heat exchanger during internal fault investigation](/__l5e/assets-v1/107e834c-b286-439b-b9b4-c5b67a05851a/work-17.jpeg) In detail ## Brands, codes and what we diagnose Every modern boiler has its own fault language. We speak all of them. [Get a fixed quote](#enquiry) ### Worcester Bosch Greenstar 4000, 8000, i, Si, CDi — full diagnostic suite. Common faults: D5 reset loop, EA ignition lockout, A1 pump failure, A21 flue gas fault. Genuine parts via local trade counter, where available. ### Vaillant Vaillant gas boilers diagnosed and repaired on a code-by-code basis — we read the fault log, test the suspect component before we replace anything. ### Ideal Logic, Logic Max, Vogue, Vogue Max. Common: L2 ignition lockout, L9 ignition fan, F1 low pressure. Strong parts availability locally for Scunthorpe and Doncaster engineers. ### Baxi & Potterton Baxi 600, 800, Duo-Tec; Potterton Promax, Titanium. E133 ignition, E168 fan, E160 sensor — diagnosed and repaired. ### Glow-worm, Main, Alpha Same diagnostic principles, fewer parts in van but next-day available through local trade. common fault codes diagnosed routinely. ### Older non-condensing units Worcester 24CDi, Ideal Classic, Glow-worm Energy — we still repair them where it's economical, and tell you straight if it isn't. ### System & controls faults Not every 'boiler fault' is in the boiler. Stuck three-port valves, failed pumps, dead programmer outputs, room stats not calling — diagnosed at system level, not just at the appliance. Frequently asked ## Straight answers, in plain English. Can't see your question? Ring Azim directly on [07576 593045](tel:07576593045). ### How much is a diagnostic call-out? Flat fee of a small flat fee. That covers the diagnosis. Any repair you proceed with is quoted in writing on top — and the diagnostic fee is deducted from larger repairs over £300. ### How quickly can you attend? Mon–Fri 8am–5pm across Scunthorpe, Brigg, Messingham, Scotter and Barton-upon-Humber. Mon–Fri 8am–5pm for Hull, Grimsby and Doncaster — earlier you call, better the slot. ### What if you can't fix it on the first visit? If we need to order a specific part, we leave the system safe, give you a fixed-price quote, and return as soon as the part arrives. No charge for the second visit beyond the original fee and parts. ### Will you tell me if it's not worth fixing? Yes — honestly. We'll show you the cost of repair vs the cost of replacement and the realistic remaining life. No commission, no upselling — your call. ### Do you cover oil-fired boilers? No — we cover gas appliances only. We don't carry out oil-fired (OFTEC) work. ### Is my boiler too old to be worth repairing? Generally we'd consider replacement once a boiler is 14+ years old, out of warranty, and needing £300+ of repair. Under that, repair usually wins. We'll lay out the numbers either way. ### Will my home insurance cover this? Some home insurance policies cover unexpected breakdowns — we'll provide a written report and invoice that satisfies most insurers. Check your policy wording or ask us before we attend. ### Do you guarantee the repair? 12-month workmanship guarantee on every repair, in writing. Same fault returns, we come back free. Related services ## More from A T Plumbing & Heating [View all services](/services) [Heating Repairs & Servicing ](/services/heating)[Boiler Installations ](/services/boiler-installations)[Gas Safety Certificates ](/services/gas-safety-certificates) Next step ## Boiler down? Get a real diagnosis today. Diagnostic visits Mon–Fri 8am–5pm across North Lincolnshire and the Humber. Fixed-price repair in writing, parts proven faulty before they are swapped. [Request a Free Estimate](/contact) [07576 593045](tel:07576593045) - Gas Safe registered - G3 certified - Fully insured - Family-run · Gas Safe registered 556262 Phone [07576 593045](tel:07576593045) Email [info@atplumbing.co.uk](mailto:info@atplumbing.co.uk) Based 17 High Burgage, Winteringham, DN15 9NE Hours Mon–Fri 8am–5pm · Sat/Sun closed [![A T Plumbing & Heating (Lincs) Limited](/__l5e/assets-v1/4b011dd3-2dc4-4e91-b5f8-70b484305ad1/at-plumbing-heating-logo.png)](/) Gas Safe registered plumbing & heating engineers based in Winteringham, North Lincolnshire. Family-run · Gas Safe registered 556262 across Scunthorpe, Hull, Grimsby, Doncaster and the wider Humber region. [](https://www.facebook.com/ATPlumbingandHeating556262) ## Services - [Plumbing](/services/plumbing) - [Heating](/services/heating) - [Boiler Installations](/services/boiler-installations) - [Fault Finding](/services/fault-finding) - [Full Central Heating Installation](/services/central-heating-installation) - [Bathroom Fitting](/services/bathroom-fitting) - [Gas Safety Certificates](/services/gas-safety-certificates) - [Underfloor Heating](/services/underfloor-heating) - [Unvented Cylinders (G3)](/services/unvented-cylinders) ## Areas - [Scunthorpe](/service-areas/scunthorpe) - [Hull](/service-areas/hull) - [Grimsby](/service-areas/grimsby) - [Doncaster](/service-areas/doncaster) - [Brigg](/service-areas/brigg) - [Kirton Lindsey](/service-areas/kirton-lindsey) - [Messingham](/service-areas/messingham) - [Scotter](/service-areas/scotter) - [Barton-upon-Humber](/service-areas/barton-upon-humber) ## Contact - [07576 593045](tel:07576593045)[07927 450996](tel:07927450996) - [info@atplumbing.co.uk](mailto:info@atplumbing.co.uk) - 17 High Burgage, Winteringham, DN15 9NE Family-run · Gas Safe registered 556262 · Company No. 11810388 © 2026 A T Plumbing & Heating (Lincs) Limited. 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