Boiler
E1
The E1 error code on a Baxi boiler is a lockout fault that typically signals a problem with ignition — meaning your boiler has tried to light and failed, so it has shut itself down as a safety precaution. It’s one of the most common Baxi fault codes and, while it can sometimes be resolved with a simple reset, it can also point to a more serious underlying issue that requires a Gas Safe registered engineer. In this guide, we’ll explain exactly what the E1 code means, walk you through the safe steps you can try at home, and help you decide whether a repair or a replacement is the right call.
What does this error mean?
The E1 error code on Baxi boilers — including popular models in the Baxi 100, 200, 400, 600, and Platinum ranges — is an ignition lockout fault. In plain English, your boiler has attempted to ignite the burner (usually two or three times), failed to detect a flame, and has shut itself down to prevent a dangerous build-up of unburned gas. This is a safety feature, not a malfunction in itself. The boiler’s control board monitors the ignition sequence via a component called the flame sensor (or ionisation probe). If it doesn’t detect a flame within a set time window, it triggers the E1 lockout and displays the fault code on the display panel. Until the underlying cause is identified and resolved, the boiler will not restart automatically — it needs either a manual reset or an engineer’s intervention.
Est. repair cost
£90–£150 for a Gas Safe engineer call-out and minor repair (e.g. ignition electrodes or flame sensor replacement); £200–£400+ if a gas valve or PCB replacement is required
🔍 Likely causes
🛠️ Step-by-step fix
Step 1 — Check your gas supply first: Before doing anything with the boiler, check that other gas appliances in your home (such as your gas hob or oven) are working normally. If they’re not, the issue is with your gas supply, not your boiler. Contact your gas supplier or call the National Gas Emergency line on 0800 111 999 immediately if you suspect a supply issue or smell gas.
Step 2 — Check your prepayment meter (if applicable): If you have a prepayment gas meter, check that you have sufficient credit. A depleted meter is a surprisingly common cause of ignition lockouts and is easily overlooked.
Step 3 — Perform a boiler reset: Locate the reset button on your Baxi boiler — on most models this is a dedicated button or a symbol on the display panel (often a flame with a cross, or a circular arrow). Press and hold it for approximately 3 seconds until the boiler attempts to restart. Allow the boiler a full minute to complete its ignition sequence. Do not reset the boiler more than twice without investigating further, as repeated resets without resolving the cause can mask a worsening fault.
Step 4 — Check the condensate pipe (in cold weather): If the E1 code appears during freezing temperatures, locate your condensate pipe — this is typically a white plastic pipe (usually 21.5mm or 32mm diameter) that runs from the boiler to an external drain or soakaway. If it feels frozen solid, you can carefully thaw it by pouring warm (not boiling) water along the pipe or wrapping it in a warm cloth. Once thawed, reset the boiler as in Step 3.
Step 5 — Check your boiler pressure: While low pressure is more commonly associated with different fault codes, a pressure reading below 1 bar can cause ignition issues on some Baxi models. Check the pressure gauge on the front of the boiler — it should read between 1 and 1.5 bar when cold. If it’s below 1 bar, you can repressurise the system using the filling loop (refer to your Baxi manual for your specific model), then attempt a reset.
Step 6 — Inspect the boiler manual for model-specific guidance: Baxi produces a wide range of boilers, and the E1 code can have slightly different triggers across the 100, 200, 400, 600, and Platinum series. Check your boiler’s user manual (available free on the Baxi website at baxi.co.uk) for any model-specific reset procedure or additional guidance.
Step 7 — Stop here and call a Gas Safe registered engineer: If the boiler locks out again after one or two resets, or if you cannot identify an obvious cause such as a frozen pipe or empty meter, do not attempt any further DIY. The remaining causes — faulty electrodes, a failing flame sensor, a gas valve fault, or a PCB issue — all require a qualified Gas Safe registered engineer to diagnose and repair safely. Attempting to access internal gas components yourself is illegal and extremely dangerous.
📞 When to call a professional
You should call a Gas Safe registered engineer if: the boiler continues to display E1 after one or two resets; the error returns within a short period after resetting; you can smell gas at any point (in which case, leave the property immediately, do not operate any switches, and call 0800 111 999); or you cannot identify a simple external cause such as a frozen condensate pipe or empty gas meter. When you call, tell the engineer: the boiler make and model (found on the front casing), the exact error code displayed (E1), how many times you’ve reset it, how old the boiler is, and whether the fault is intermittent or constant. This will help them arrive prepared with the most likely replacement parts — typically the ignition electrodes, flame sensor, or gas valve — saving you time and a potential return visit. You can find a Gas Safe registered engineer at gassaferegister.co.uk or by calling 0800 408 5500.
⚖️ Repair or replace?
For a Baxi boiler under 8 years old, repair is almost always the right decision. Baxi is one of the UK’s most popular boiler brands, and parts are widely available from merchants and online suppliers, keeping repair costs competitive. The most common E1 repairs — replacing ignition electrodes or the flame sensor — are straightforward jobs for an experienced engineer. If the fault lies with the gas valve or PCB, costs rise considerably, and on a boiler that’s 10 years old or more, it’s worth asking your engineer to weigh the repair cost against the boiler’s remaining lifespan. As a rule of thumb: if the repair costs more than half the price of a new boiler, or your boiler is over 12 years old and has a history of faults, a replacement is likely the more economical long-term choice. A new Baxi boiler (supplied and installed) typically costs between £1,500 and £2,800 depending on the model and your property size, and comes with a manufacturer’s warranty of up to 10 years.