Error 5 Red Flashes

Safety precautions:

1) If you smell gas or suspect a gas leak, immediately leave the property and call the gas emergency number. Do not operate electrical switches or the boiler. 2) If a carbon monoxide alarm is sounding or you suspect CO, evacuate and call emergency services. 3) If you are not confident working near mains electricity or gas appliances, stop and call a Gas Safe registered engineer.

Initial checks a homeowner can do (safe, non-invasive):

1) Note the exact display and that it is 5 red flashes. Take a photo and write down any other LEDs or messages. 2) Check for obvious external causes: has there been a recent power cut or surge? Is the electricity supply to the boiler stable (other appliances working)? 3) Check the room thermostat and programmer batteries and settings; ensure demand for heat/hot water is present. 4) Check the boiler pressure gauge is roughly between 1 and 1.5 bar (low pressure can cause other faults). 5) Look for signs of water ingress, condensation, or burn/odour around the boiler casing; if present, switch the boiler off and call an engineer.

Simple reset and power-cycle steps (try these once):

1) Use the boiler reset/selector method recommended by the manufacturer: open the control panel, set the selector to R (Reset) and hold for 5–10 seconds, or press and hold the dedicated reset button until the boiler attempts to restart. 2) If the boiler has no dedicated reset, isolate the boiler electrically at the fused spur or switch, leave isolated for 60 seconds, then restore power and attempt a normal restart. 3) After reset, wait to see if the fault clears and the boiler runs normally. Do not repeatedly reset more than two or three times if the error returns — repeated resets can mask a real safety fault.

If the fault remains after reset or returns:

1) Do not open the boiler casing or attempt PCB/PSU repairs yourself. These are live, gas-safety critical components. 2) Record the fault occurrence details: time, conditions (power cut, storm), any other error codes observed, boiler model and serial number, and take clear photos of the display and PCB label if accessible without removing covers. 3) Check external wiring connections you can safely access (room stat/programmable controller wiring) for loose terminals or recent changes. Replace thermostat batteries and try again.

When to call a professional and what to expect:

1) If the 5 red flashes persist after a reset/power-cycle, or if you observe water damage, burning smells, repeated lockouts, or other faults, contact a Gas Safe registered heating engineer. 2) Tell the engineer you saw 5 red flashes (Parameter/PSU error), give model/serial and describe any recent power events. 3) The engineer will carry out mains isolation, enter the service menu, read stored fault codes and history, check PCB voltages and connector integrity, and test associated sensors and external controllers. If parameter memory or the PSU is corrupted or failed they may attempt to reload/reprogramme parameters where possible or replace the PSU/PCB assembly. The engineer will also check for underlying causes (power surges, water ingress, poor earth/neutral, failed peripheral devices) before replacing parts.

Final guidance:

1) Do not keep resetting the boiler if the fault returns — leave it and call a Gas Safe engineer. 2) Keep a record of the fault, photos and any actions you took; have the engineer check warranty/installation date as PCB/PSU failure may be covered. 3) For safety-critical or complex electrical/PCB work, always use a qualified Gas Safe registered engineer; they will ensure safe commissioning, parameter configuration and compliance with regulations.