Johnson & Starley 2 Fault Code: Causes, Fixes & Repair Costs
What does the Johnson & Starley 2 fault code mean?
Fault Code 2 (shown as 'Display 2' on the LCD/LED panel) appears on Johnson & Starley Economaire warm air heaters when the air pressure switch fails to release from its closed position at the point in the start-up sequence when it should be open. In normal operation the combustion air fan (CAF) generates a pressure differential that the air pressure switch monitors; the switch must be in the correct state before the PCB will allow the ignition sequence to proceed. When the switch remains closed unexpectedly – whether due to contaminated tubes, a faulty switch, or a fan problem – the appliance shuts down safely and displays this code. This code is specific to the Economaire warm air heater range; Johnson & Starley's QuanTec and Reno combi/system boilers use a different fault-code scheme.
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
- Contaminated venturi, restrictor, or air pressure hoses Common
The most frequently found root cause in practice. Dust and debris can accumulate inside the venturi built into the CAF assembly, in the small restrictor fitted to the positive air hose, or on the fan blades themselves. This reduces the pressure differential the fan produces; if it drops below the roughly 0.48 mbar threshold the air pressure switch needs to operate, the switch fails to release and Display 2 is triggered. Blowing down the hoses connecting to the venturi can sometimes clear the blockage, but a thorough clean of the CAF blades and restrictor usually requires an engineer visit.
- Faulty or out-of-calibration air pressure switch Common
The air pressure switch itself can stick in the closed position, fail mechanically, or drift out of calibration over time so that it no longer responds correctly to the differential pressure being produced by the fan. If the switch fails to release even after the hoses and venturi have been checked and cleared, the switch itself will need to be replaced.
- Splits or blockages in air pressure hose connections Sometimes
Cracks, splits, or loose connections in the rubber hoses that link the venturi to the air pressure switch allow air to escape or enter incorrectly, distorting the pressure signal. Even a hairline split can be enough to prevent the switch from operating at the correct threshold.
- Combustion air fan (CAF) beginning to fail Sometimes
A fan that is worn, has a failing motor, or has deteriorated bearings may spin at a reduced speed or with inconsistent output, producing insufficient pressure differential even with clean blades and unobstructed hoses. Note that a completely dead fan more typically generates Display 3 rather than Display 2; Display 2 usually means the fan is running but struggling rather than not running at all.
- Economaire module (PCB) fault Rare
If the air pressure switch, all hoses, the venturi, and the fan motor have all been checked and are functioning correctly, the fault may lie within the Economaire module (the integrated PCB/control unit). This is the final step in the official Johnson & Starley fault-finding flowchart for Display 2 and is the least common cause.
How to fix it
- Reset the boiler once (no more than two or three attempts in total) DIY safe
Locate the reset button on the Economaire control panel and press it as described in your user guide. If the appliance starts normally and the display clears, monitor it over the next few hours. If Display 2 returns, do not keep resetting – repeated resets without resolving the underlying cause can mask a developing fault and cause further damage.
- Check that the gas supply to the property is on DIY safe
Confirm other gas appliances in the home (cooker, hob) are working normally. If there is no gas supply, contact your gas supplier rather than attempting any work on the heater.
- Call a Gas Safe registered engineer to inspect and clean the venturi and air pressure hoses Gas Safe engineer
An engineer will disconnect the air pressure hoses, blow through the venturi passage inside the CAF assembly, clean any dust from the restrictor in the positive air hose, and check for splits or loose connections. A digital manometer is used to confirm whether the fan is generating the required pressure differential. This is the most common on-site fix for Display 2 and should be the first diagnostic step the engineer performs.
- Engineer to inspect and test the combustion air fan (CAF) Gas Safe engineer
The engineer will check that the fan is spinning freely, listen for worn bearings, and measure the voltage reaching the motor. If the fan blades are dirty they will be cleaned. On older Economaires (particularly the popular '32' size) new replacement fans may no longer be available; a specialist may instead fit a replacement motor into the original housing, which restores function but does carry a higher labour cost.
- Engineer to test and replace the air pressure switch if necessary Gas Safe engineer
Using a manometer and multimeter, the engineer will verify that the switch opens and closes at the correct pressure differential. A switch that is stuck, out of calibration, or giving inconsistent readings should be replaced with the correct-specification part for the Economaire model.
- Engineer to check wiring continuity between the fan and the PCB Gas Safe engineer
Deteriorated wiring or loose terminals between the CAF and the Economaire module can interrupt the control signals. The engineer will check connector integrity and confirm 230 V ac is present at the relevant terminals; if it is absent despite the fan and wiring being sound, the module itself is implicated.
- Engineer to replace the Economaire module if all other components are satisfactory Gas Safe engineer
This is the final step in the official fault-finding sequence. The Economaire module (integrated PCB and control unit) is replaced only once all other possible causes have been ruled out, as it is the most expensive component involved.
Parts you may need
- Air pressure switch (Economaire-compatible) · from £35
- Combustion air fan motor (refurbished/replacement for '32' and similar sizes) · from £120
- Air pressure hose and restrictor set · from £18
- Economaire module (PCB/control unit) · from £220
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–£380, depending on the underlying cause.
Frequently asked questions
Can I fix Johnson & Starley Fault Code 2 myself?
Not safely, and not legally. While you can press the reset button once or twice as described in your user guide, any work beyond that – removing hoses, testing the air pressure switch, cleaning the venturi, or replacing components – must be carried out by a Gas Safe registered engineer. Attempting gas appliance repairs yourself is illegal in the UK and can be extremely dangerous.
Why has Display 2 appeared but my Economaire seemed to be running fine before?
Fault Code 2 can appear gradually as the venturi or CAF blades accumulate dust during normal use. The contamination reduces the pressure differential produced by the fan until it eventually drops just below the 0.48 mbar threshold the air pressure switch requires. The boiler may have been operating on the margin for some time before the fault became consistent. Annual servicing — which includes cleaning the CAF and hoses — is the best way to prevent this.
What is the difference between Display 2 and Display 3 on a Johnson & Starley Economaire?
Display 2 means the air pressure switch has failed to release (it is stuck closed when it should open). Display 3 typically indicates the fan has failed to start at all — so the switch never receives any pressure signal. If your Economaire is completely silent when it should be starting up, Display 3 is more likely. Display 2 usually occurs when the fan is running but not producing quite enough pressure, often due to contamination.
How much does it cost to repair a Johnson & Starley Economaire showing fault code 2?
Most Display 2 repairs fall in the range of £120 to £380. A simple clean of the venturi and hoses during an engineer call-out sits towards the lower end, while replacing the air pressure switch adds £100–£150 in parts and labour. Fan motor work is typically £225–£375 given the specialist nature of sourcing parts for older Economaire units. Replacing the Economaire module (PCB) can cost £300–£500 and is comparatively rare — if an engineer quotes for this early without first eliminating the more common causes, it is worth seeking a second opinion.