Remeha A.02.06 Fault Code: Causes, Fixes & Repair Costs
What does the Remeha A.02.06 fault code mean?
The A.02.06 code is Remeha's water pressure warning, meaning the system pressure has dropped below the minimum threshold needed for safe, reliable operation. Unlike a full lockout, the boiler may continue running in a reduced state, but the fault must be addressed promptly. Left unattended, the warning can escalate first to a blocking (boiler stops heating) and then to a lockout (manual reset required). The target pressure for most Remeha systems is between 1 and 2 bar when cold; anything below 1 bar will typically trigger this warning.
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
- Recent radiator bleeding Common
Bleeding radiators releases trapped air but also removes a small volume of water from the sealed system, causing the pressure gauge to drop. If radiators were recently bled and the pressure is slightly below 1 bar, this is almost certainly the cause.
- Gradual or minor system leak Common
Even a slow drip at a radiator valve gland, pipe joint, or towel rail connection can reduce pressure over days or weeks. Check all visible pipework, radiator valves, and the boiler casing for damp patches, staining, or corrosion marks. A leak that is hard to spot may be traced by watching the pressure gauge fall repeatedly after repressurising.
- Faulty or waterlogged expansion vessel Sometimes
The expansion vessel contains a rubber diaphragm that absorbs the increase in water volume as the system heats up. If the diaphragm perishes or the vessel loses its nitrogen charge, it can no longer buffer pressure changes — causing pressure to swing wildly and sometimes forcing water out through the pressure relief valve (PRV). You may notice the PRV dripping outside if this is the issue.
- Pressure relief valve weeping Sometimes
A PRV that has been opened repeatedly (perhaps by high pressure events) can develop a partial seal failure, allowing water to escape slowly even when system pressure is normal. The PRV discharge pipe typically exits through an outside wall; check for drips or mineral staining.
- Faulty water pressure sensor Rare
The sensor that measures system pressure can fail or drift, sending an inaccurate low-pressure reading to the boiler's control board even when the actual pressure is fine. This is less common but worth considering when pressure reads correctly on an external gauge yet the warning persists.
How to fix it
- Check the pressure gauge DIY safe
Locate the pressure gauge on the boiler — it may be a dial gauge or a digital reading in the boiler's display menu. A healthy cold-system pressure is typically 1–1.5 bar. If it reads below 1 bar, the system needs topping up. If it reads within range and the warning is still showing, the sensor itself may be at fault.
- Top up the system pressure using the filling loop DIY safe
Most Remeha boilers use either a built-in Easyfill link (a green lever or knob under the appliance) or an external braided filling loop with two isolation valves. Slowly open the valve(s), watch the gauge rise to around 1.2–1.5 bar, then close the valve(s) fully. Never overfill beyond 2 bar. Refer to your boiler's user guide for the exact filling procedure for your model.
- Reset the boiler DIY safe
Once pressure is back in range, press and hold the reset button (usually marked with a flame and line symbol) for a few seconds until the boiler attempts to restart. If it fires up and the warning clears, monitor the pressure over the next few days. Avoid resetting more than two or three times without understanding why the fault appeared.
- Inspect all accessible pipework and radiators for leaks DIY safe
Walk around the property checking every radiator, thermostatic radiator valve (TRV), lockshield valve, and any visible pipe runs for signs of dripping water, damp patches on walls or floors, or white limescale residue. Also check under the boiler casing (if accessible without tools) and look outside for drips from the PRV discharge pipe.
- If pressure keeps dropping, arrange a Gas Safe engineer visit Gas Safe engineer
If the system pressure falls below 1 bar again within a few days of repressurising — particularly without any obvious external leak — there is likely an underlying problem such as a failing expansion vessel, a weeping PRV, or a hidden internal leak. A Gas Safe registered engineer can test the expansion vessel charge, inspect internal components, and carry out the necessary repair safely. Do not continue to repressurise repeatedly as a long-term fix.
Parts you may need
- Expansion vessel (8–24 litre, compatible with Remeha) · from £55
- Expansion vessel diaphragm / bladder (where serviceable) · from £20
- Water pressure sensor · from £25
- Pressure relief valve (3 bar) · from £18
- Filling loop / Easyfill link assembly · from £15
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 £80–£350, depending on the underlying cause.
Frequently asked questions
Can I fix the Remeha A.02.06 warning myself?
In many cases, yes. If the system pressure has simply dropped below 1 bar — perhaps after bleeding radiators — repressurising via the filling loop is a straightforward DIY task described in your boiler's user guide. However, if the pressure keeps dropping or you cannot find a reason for the loss, you should call a Gas Safe engineer rather than repeatedly topping up, as you could be masking an internal leak or a failed expansion vessel.
How often should my boiler lose pressure?
A properly sealed central heating system should hold its pressure for months without needing a top-up. Losing more than around 0.2–0.3 bar in a few days is a sign something is wrong. Occasional small drops over a year are normal due to dissolved gases escaping, but frequent drops — especially after repressurising — almost always point to a leak or a faulty expansion vessel.
How much does it cost to fix low boiler pressure in the UK?
If you can repressurise the boiler yourself, there is no cost. An engineer callout to do the same typically runs £80–£150 depending on your area. If an expansion vessel needs recharging or replacing, expect £150–£350 including parts and labour. A pressure sensor or PRV replacement usually sits in the £100–£200 range all-in. Complex internal leaks or a heat exchanger issue can push costs considerably higher — a Gas Safe engineer's diagnosis will clarify what is needed.
What is the correct pressure for a Remeha boiler?
Remeha recommends a cold-fill pressure of 1–2 bar for most of their residential combi and system boilers. A setting of around 1.2–1.5 bar when the system is cold gives a comfortable margin — it will rise slightly when the heating is running, but should not exceed 2.5–3 bar at full operating temperature. If the gauge regularly climbs above 2.5 bar when hot, the expansion vessel may not be doing its job correctly.