Alpha Boiler Fault Codes – Causes, Fixes & When to Call an Engineer

Even reliable boilers can develop faults. If your Alpha boiler displays an error code or starts flashing its warning lights, the code can help identify the problem.

Some issues, such as low boiler pressure, may be straightforward to resolve. Others involve gas, ignition, electrical or flue components and need attention from a qualified Gas Safe registered engineer.

Common Alpha Boiler Fault Codes

Alpha E01 Fault Code

The Alpha E01 fault code indicates an ignition problem. The boiler has attempted to light the burner but has failed to detect a flame.

Before calling an engineer, check that your gas supply is working by testing another gas appliance.

If the gas supply is fine, possible causes include a problem with the ignition or flame sensor electrode, damaged pressure tubes, a faulty ignition generator or lead, or incorrect gas valve settings.

These faults can involve removing the boiler casing and working with gas components. Do not attempt this yourself. A Gas Safe registered engineer should diagnose and repair the fault.

Alpha E10 Fault Code

An Alpha E10 fault code indicates low water pressure in the heating system. The boiler may shut down when the pressure falls below its required level.

You can often resolve low pressure by repressurising the system. Follow the instructions in your Alpha boiler manual and use the filling loop if your model has one. After repressurising, the pressure will typically need to be around 1 to 1.5 bar.

If the pressure keeps dropping, however, there may be an underlying leak or another fault in the heating system. Repeatedly topping up the pressure is not a permanent fix, so arrange for an engineer to investigate.

Alpha E20 Fault Code

The Alpha E20 fault code indicates a problem detecting a flame. The boiler shuts down as a safety measure. Possible causes include a problem with the gas supply, flame sensor or ignition unit.

This fault needs professional diagnosis because the cause may involve internal boiler or gas components.

Alpha E96 Fault Code

An Alpha E96 fault can indicate a faulty fan or a blocked flue. The fan helps expel combustion gases from the boiler, while the flue safely carries those gases outside. Both faults require professional attention because internal boiler components may need to be inspected.

Common Alpha Boiler Warning Lights

Alpha boilers can also indicate faults through their warning lights. The exact meaning can depend on the boiler model, so check your user manual if the light pattern differs from the examples below.

Solid Red Light

A solid red “A” light can indicate that the burner has failed to ignite.

You can try resetting the boiler by turning the selector switch to the reset position and leaving it there for around 25 to 30 seconds.

If the boiler does not restart, there may be a problem with the burner, gas valve or another component. A Gas Safe registered engineer should investigate.

Alpha Boiler Flashing A and B

If the red “A” and yellow “B” lights are flashing together, the burner may be failing to ignite.

Try resetting the boiler according to the instructions for your model. If the fault remains, possible causes include the burner fan, gas valve or ignition connections.

A qualified engineer should inspect the boiler rather than attempting to repair these components yourself.

Flashing Red A Light

A flashing red “A” light, with the yellow light off, can indicate an overheating problem. Possible causes include a pump fault, restricted or blocked pipework, a flue sensor problem, or air in or around the heat exchanger.

These faults need professional diagnosis and repair.

No Hot Water

If your Alpha boiler is running but you have no hot water, check the basics first: is the boiler receiving power, does the fan run but ignition fail, does the boiler fire up and then cut out, and is there an error code or warning light?

A faulty ignition system, gas valve, diverter valve or flow sensor can cause hot-water problems. An engineer can test the relevant components and identify the cause.

Low Boiler Pressure

If the pressure gauge is low or the boiler displays E10, the heating system has lost pressure. You can repressurise the boiler according to the manufacturer's instructions. If the pressure falls again, arrange for an engineer to check for a leak or another underlying fault.

Water Not Hot Enough

If the hot water is only lukewarm, two possible causes are a faulty temperature sensor or limescale build-up. An engineer can test the sensor and check the boiler for scale or other component faults.

List of Alpha Boiler Error Codes

The table below gives an overview of the Alpha fault codes covered on this page — not a complete list of every code across the Alpha range.

If You Smell Gas

Do not remove the boiler casing or attempt to repair gas, ignition or flue components yourself. If you smell gas at any point, stop immediately, do not operate light switches or naked flames, turn off the gas supply at the meter if it's safe to do so, ventilate the area, and call the National Gas Emergency Service on 0800 111 999 straight away.

When to Call an Engineer

Some basic checks and resets are safe to try when recommended by your boiler manual. Repeated faults, persistent low pressure, overheating warnings and ignition problems need further investigation.

For gas-related problems, use a Gas Safe registered engineer.

If your Alpha boiler keeps developing faults, an engineer can diagnose the underlying problem rather than simply resetting the boiler each time.

Your Next Steps for Boiler Repairs

Regular boiler servicing can help identify problems before they develop into unexpected breakdowns. However, if an older boiler needs frequent repairs, replacement may eventually be more practical than continuing to repair individual components.

If you need help diagnosing or repairing an Alpha boiler in London, Serviceteam can assess the fault and advise on the appropriate repair via our boiler repair in London service.

Frequently Asked Questions - (FAQs)

The Alpha E10 error indicates low water pressure in the heating system. It can be caused by a leak, recent radiator bleeding or the system simply needing to be repressurised.

E01 is an ignition fault. The boiler has attempted to ignite but has not detected a flame. Possible causes include the ignition system, flame sensor, gas valve or related components.

Flashing A and B can indicate a burner ignition problem, although the exact meaning can vary between Alpha models. Check your boiler manual for the specific light sequence. If the fault remains, arrange for an engineer to inspect the boiler.

A flashing red light can indicate a fault or lockout. Possible causes include overheating, low pressure or ignition problems. Check the displayed fault code and your boiler manual before arranging further repairs.

Repeated shutdowns can be caused by low pressure, overheating, a blocked condensate pipe, thermostat problems or another fault causing the boiler to lock out.

Check the pressure gauge and look for a fault code. If the boiler continues to shut down, have it inspected by a qualified engineer.