More Greenstars are installed in London homes than any other boiler — which is exactly why our engineers see every fault they produce, week in and week out. Same-day repair on EA lockouts, E9 overheats, low-pressure faults and everything in between, by Gas Safe engineers who work on Worcester Bosch daily.
E9
F0
Average reply under 10 minutes. No obligation.
Worcester Bosch is Britain’s best-selling boiler brand for good reason: build quality is genuinely a step above most of the market, and when a Greenstar does fault it’s almost always a discrete component, not a terminal problem. That means fast, sensible repairs for years past the point that cheaper boilers would have been scrapped. Alongside our wider London-wide boiler repair service, we run Worcester Bosch callouts every day of the week, and the patterns are consistent enough to diagnose most of them over the phone.
The single biggest winter caller is the EA lockout — an ignition or flame-detection fault that, on maybe eight jobs out of ten in a cold snap, turns out to be a frozen white condensate pipe running out of an exterior wall, not a fault inside the boiler at all. We tell people that on the phone before charging anyone a visit. Beyond EA, we see E9 overheat lockouts (usually a stuck pump, blockage or heat exchanger complaining after years of sludge), C6 fan-speed faults, D1 sensor errors, and quiet low-pressure faults that creep down over weeks until the heating stops firing. On older Greenstar CDi combis — still very common in London flats — the classic symptom is hot water working fine while heating dies, or vice versa: that’s diverter valve wear, and we carry the parts.
The one Worcester Bosch weakness worth naming is scale on the aluminium heat exchanger of older Greenstar models in London’s hard-water postcodes — which is exactly why annual boiler servicing pays for itself several times over on a Greenstar. Look after it, and it looks after you.
E9
A cheap sensor with a big impact — the boiler runs blind on temperature. Straightforward swap.
F0 / F7
Low pressure (no code)
Our engineers work across the current Greenstar 2000, 4000 and 8000 Life & Style ranges, the long-serving Greenstar i, Si Compact and CDi Classic / Compact / Highflow families, and the older Junior units still turning over in London rentals. Parts availability across the range is excellent — even for boilers pushing 15 years, most components are still stocked or next-day from Bosch’s London depot. That said, on older Greenstars facing a heat exchanger or PCB job we’ll always give you the honest repair-vs-replace numbers on site rather than sell you a big repair you’d regret in eighteen months. If replacement is genuinely the smarter call, see our new Worcester Bosch installation options.
Worcester’s fault display is one of the clearest in the industry — a letter and a number that map cleanly to a component. Below are the codes we clear most often in London homes. If your Greenstar is showing something else, call and read it to us; we’ll tell you what it means for free.
EA ignition electrode / flame sensor
Diverter valve (CDi combi)
“EA at 6am, family with a newborn. Diagnosed frozen condensate over the phone, told them how to thaw it safely, followed up with an insulation visit the same afternoon.”
— FULHAM
— CHISWICK
If your Greenstar is still inside its 10–12 year Worcester Accredited Installer warranty, we always check the registration first. If it’s covered, we tell you and route it to Worcester rather than charge you. Out of warranty, we use genuine or manufacturer-approved parts to protect any workmanship guarantee.
Yes — electrodes, sensors, fans, diverter kits and PCBs for every current Greenstar range travel in the van. Rarer parts for older CDi and Junior models are next-day from Bosch’s London depot.
