Johnson & Starley 1 Fault Code: Causes, Fixes & Repair Costs
What does the Johnson & Starley 1 fault code mean?
Fault Code 1 on Johnson & Starley boilers indicates that the boiler has attempted to light the burner and failed to detect a stable flame, resulting in a safety lockout. On combi and heat-only models such as the Quantec HR28C, the display typically shows 'E1'. On warm air units like the Economaire, a single red LED character is visible through a small window in the front panel — Code 1 on that chart means the same thing: ignition has been attempted but no flame was established or detected. Once in lockout the boiler stops all heating and hot water until the fault is resolved and the unit is reset.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Gas supply interrupted or pressure too low Common
If the gas cock is closed, the meter is off, or the supply pressure at the boiler inlet falls below around 18 mbar, the burner simply cannot light. In very cold weather the gas regulator or meter can briefly freeze, cutting supply pressure and triggering this lockout.
- Loose or disconnected wiring to the ESYS ignition module Common
Johnson & Starley warm air boilers use an ESYS ignition control module mounted on the gas valve. A loose lead — particularly the flame-sensing electrode lead not pressed fully onto its tag — is a well-known field cause of flame failure faults including Code 1. The connection looks intact visually but makes no electrical contact, so the control board never receives a flame signal.
- Faulty or incorrectly gapped ignition electrode Common
The ignition electrode produces the spark that lights the burner. If the electrode is cracked, contaminated with carbon, or the spark gap has drifted from the specified 4 mm, sparking will be weak or absent and ignition will fail repeatedly.
- Flame sensor fault or degraded sensing electrode Sometimes
If the burner does ignite briefly but the boiler then shuts down on lockout, the flame sensor (detection electrode) or its wiring harness may be faulty. A failed sensor cannot confirm to the control board that a flame is present, so the board shuts off the gas as a safety measure.
- Failed ESYS ignition control module Sometimes
The ESYS module piggy-backed onto the gas valve controls the ignition sequence and monitors the flame signal. If the module itself has failed, the boiler will lock out on Code 1 even when all wiring and electrodes are in good condition. Replacing the ESYS module resolves this.
- Gas valve failure Sometimes
If the gas valve is not opening correctly — either due to a solenoid fault or internal wear — no gas reaches the burner. An engineer can check resistance between the outer pins (approximately 114 Ω expected) and confirm 24 V DC is present at the valve during an ignition attempt to determine whether the valve needs replacement.
- Blocked condensate pipe Rare
On condensing models, a frozen or blocked condensate pipe can cause the boiler to fault and prevent a successful restart. Although not a direct ignition fault, it can produce a Code 1 lockout scenario if the boiler cannot complete its start-up sequence.
How to fix it
- Check your gas supply is on DIY safe
Confirm the gas isolation cock on the supply pipe to the boiler is in the open position (handle in line with the pipe). Check that other gas appliances in the property — hob, fire — are working normally. If nothing is working, contact your gas supplier, not an engineer.
- Thaw a frozen condensate pipe if applicable DIY safe
On condensing models, locate the white plastic condensate pipe that exits the boiler and runs to a drain. In freezing weather it may be blocked with ice. You can carefully pour warm (not boiling) water along the pipe to thaw it. Once clear, attempt a reset.
- Reset the boiler — up to two or three times only DIY safe
Press and hold the reset button as described in your user manual until the boiler attempts to re-light. A single reset is sometimes enough if the initial lockout was caused by air in the supply after maintenance or a gas interruption. Do not reset more than two or three times — repeated unsuccessful resets will not fix an underlying fault and can mask important safety information.
- If the fault returns, stop and call a Gas Safe registered engineer Gas Safe engineer
All further diagnosis involves checking gas pressure at the boiler inlet, testing voltage and resistance at the gas valve, inspecting the ESYS module connections, and examining the ignition and flame-sensing electrodes. These checks require gas-safe tools, access to the gas train, and Gas Safe registration. Do not attempt them yourself.
- Engineer to inspect ESYS module wiring and connections Gas Safe engineer
The engineer should check that all leads to the ESYS ignition module are fully seated — in particular the flame-sensing electrode lead. A lead that appears connected but has not clicked fully onto its tag is a common cause of persistent Code 1 faults on warm air models.
- Engineer to check and test the ignition and detection electrodes Gas Safe engineer
The engineer will inspect both electrodes for cracks, carbon tracking, and correct positioning. The ignition spark gap should measure 4 mm. Both electrodes and their harnesses should be tested for continuity. Damaged or out-of-spec components are replaced at this stage.
- Engineer to verify gas pressure and gas valve operation Gas Safe engineer
Supply pressure at the boiler inlet must exceed 18 mbar. The engineer will also confirm approximately 24 V DC is reaching the gas valve during the ignition attempt and measure coil resistance (around 114 Ω between the outer pins). A valve that fails these checks is replaced.
- Engineer to test or replace the ESYS ignition module if all other checks pass Gas Safe engineer
If wiring, electrodes, and gas supply are all satisfactory but Code 1 persists, the ESYS module itself has likely failed and needs replacement. This is a specialist part — finding an engineer with Johnson & Starley experience is recommended.
Parts you may need
- Ignition electrode · from £35
- Flame detection electrode · from £30
- Electrode lead / ignition harness · from £25
- ESYS ignition control module · from £120
- Gas valve (Quantec / warm air range) · from £180
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £120–£350, depending on the underlying cause.
Frequently asked questions
Can I fix Johnson & Starley Fault Code 1 myself?
The only homeowner-safe actions are checking the gas is on, thawing a frozen condensate pipe, and pressing reset up to two or three times. All further work — checking gas pressure, testing the electrodes, inspecting the ESYS module, or touching the gas valve — must be carried out by a Gas Safe registered engineer. Attempting gas work without registration is illegal and dangerous.
Why does my boiler keep coming back to Code 1 after I reset it?
A fault that returns within a short time after resetting almost always points to an underlying component issue rather than a one-off air-lock. The most common culprits on Johnson & Starley units are a loose lead on the ESYS ignition module, a degraded flame-sensing electrode, or a gas valve that is not opening fully. An engineer will work through these systematically to find the root cause.
How much will it cost to repair a Johnson & Starley Code 1 fault?
Most repairs that cause Code 1 cost between £120 and £350 once you include the engineer's call-out, diagnosis, parts, and labour. A simple electrode replacement or reconnecting a loose ESYS lead sits at the lower end; replacing the gas valve typically falls in the £200–£300 range. A PCB replacement, if needed, can push costs to £350–£450 — but PCB failure is a less common cause of this specific code. Always get two or three quotes from Gas Safe engineers, as rates vary by region.
Is Johnson & Starley a specialist boiler that any engineer can work on?
Johnson & Starley warm air units in particular are less common than mainstream combi boilers, and not all heating engineers will be familiar with the ESYS module or the specific ignition system layout. It is worth asking an engineer whether they have experience with Johnson & Starley or warm air heating systems before booking, as this can speed up diagnosis considerably.