Overview
The "No display" condition on an Ideal Logic Max / Logic Plus System boiler means the front panel display is blank or not showing any information. It usually indicates a loss of power to the boiler electronics, a failed display module, a blown external fuse or isolated fused spur, a failed internal transformer or PCB fault, or very low mains voltage. In some cases the boiler electronics are powered but the display ribbon or display board has failed so the boiler may still operate while the screen remains blank. Severity is moderate to high. A blank display prevents you seeing fault codes and status, and the boiler may not provide heating or hot water if the issue involves the main control electronics or a power supply fault. Simple external checks (fused spur, consumer unit, mains supply) are suitable for a homeowner, but internal electrical or gas-related repairs, printed circuit board or display-module replacement, and any work inside the boiler must be done by a qualified Gas Safe engineer or a competent electrician. If you smell gas, see electrical burning, or suspect an electrical supply problem, treat it as an emergency and get professional help straight away.
Troubleshooting Steps
Safety precautions:
1. If you smell gas or detect burning or smoke, evacuate, turn off the gas at the meter if you can do so safely, and call the emergency number for your gas supplier and/or 999. Do not attempt repairs.
2. Always isolate electrical supplies before opening or touching the boiler casing. If you are not competent with electrical testing, stop and call a qualified electrician or Gas Safe engineer.
3. Do not attempt to repair gas components, PCB or internal wiring yourself. Internal work must be carried out by a Gas Safe registered engineer.
Initial checks a homeowner can do (no tools or basic checks):
1. Check other electrical sockets and lights in the house to confirm mains power is present.
2. Check the consumer unit (fuse box) for tripped MCB/RCDs and reset them if you can safely do so. Note any immediate re-trips and do not repeatedly reset.
3. Locate the boiler fused isolator/fused spur (usually a small switch box near the boiler). Make sure the switch is in the ON position and the cover is closed.
4. If your boiler has an external power switch on the front or an on/off switch, ensure it is switched on.
5. Try a simple power cycle: turn the boiler off at the fused spur or consumer unit for 30 seconds, then restore power and see if the display returns. Press the boiler RESTART button if available and if the display briefly appears.
Further diagnostic steps (only attempt if you are electrically competent):
1. If you are confident and trained to use a multimeter, check for 230 V AC at the output of the fused spur to confirm power is reaching the boiler. If there is no voltage at the fused spur, the problem is upstream (consumer unit, wiring, or mains) and you should call an electrician.
2. If 230 V is present at the fused spur but the display is still blank, you can check for voltage at the boiler incoming terminals (L and N) with the boiler isolated off and then repowered for testing. If power reaches the boiler but the display remains dead, the fault is internal (transformer, PCB, display module, or connections).
3. If the boiler appears to run (heating/hot water functioning) despite no display, the issue is likely the display panel or its ribbon connector. Powering down and back up can sometimes reseat connectors, but avoid opening the boiler while live; do this only if competent and safe.
4. If the boiler does not run and there is no display and there are no sounds or signs of life from the boiler (no fan, no clicks), suspect a failed PCB or internal power supply. Do not probe internal circuitry unless qualified.
What to try if initial checks fail to restore display:
1. Replace an external fused spur fuse only if you can access it and are comfortable doing so; always replace with the same fuse rating. If the fuse blows again immediately, stop and call a professional.
2. If consumer unit tripping keeps happening after reset, do not continue to reset; call an electrician.
3. If mains voltage measurements show low or unstable voltage, contact your electricity supplier.
4. If power is present at the boiler but the display stays blank or the display flickers/intermittently works, stop further DIY work and contact a Gas Safe registered engineer. The likely fix is replacement or repair of the display board, connector, transformer or main PCB.
When to call a professional:
1. Call a Gas Safe registered engineer if the display remains blank after you have checked the fused spur and consumer unit, if the boiler will not fire, or if there are internal faults suspected. A Gas Safe engineer will handle PCB/display replacement and any gas-related tests or repairs.
2. Call a qualified electrician if you find no power at the fused spur, repeated tripping at the consumer unit, or other signs of household electrical faults.
3. If the boiler is under warranty, contact the manufacturer or your installer before any intrusive work.
Record keeping and safety note:
1. Note the boiler model, serial number and any visible labels before the engineer visit to speed diagnosis.
2. Do not open the boiler casing while it is live. Internal electronic and gas work must be carried out by a Gas Safe engineer. No internal component replacements or PCB swaps should be attempted by unqualified persons.
If these homeowner checks do not restore the display or the boiler remains inoperative, arrange an appointment with a Gas Safe registered engineer and/or a qualified electrician to diagnose and repair the fault.
Helpful Resources
Boiler Manual
Download the official PDF manual for the Ideal Logic Max System / Logic Plus System.