Seeing A.02.06 on a Baxi 800 System 2 means the boiler has detected low pressure in the sealed heating circuit. Baxi’s current error-code table gives the official meaning as “Low system pressure in heating circuit”. It is a useful warning, but it does not identify the reason pressure is low.
The boiler may still appear to have power while heating performance changes. Treat the code as a prompt to make a few safe observations, consult the correct user guide and arrange repair if the warning remains or returns.
What the Baxi A.02.06 warning means
A sealed heating system uses water under pressure to carry heat from the boiler around radiators and back again. The pressure shown by the external gauge changes a little as the system warms and cools. A.02.06 appears when the boiler registers that the heating-circuit pressure is below the expected range.
This wording matters. A.02.06 describes the condition the boiler has detected; it does not prove that a particular component has failed. Pressure can fall for more than one reason, and the display alone cannot tell a homeowner which one applies.
A.02.06 is also distinct from Baxi’s H.02.07 warning, which the manufacturer describes as permanently low heating-circuit pressure. If you record the complete code exactly, an engineer can tell which message the appliance showed rather than working from a general description such as “low pressure”.
What you may notice at home
The heating may be slow to warm, some radiators may remain cool, or the boiler may stop responding to a heating demand. Because the Baxi 800 System 2 is a system boiler used with a separate hot-water cylinder, reduced boiler operation can also affect how quickly stored hot water is reheated.
Symptoms vary. You might see only the warning and a low gauge reading, or you may notice that the system works briefly before the code returns. Do not use the amount of heat in one radiator as proof of the cause. Record what happens across the home and whether the code appears when heating or cylinder reheating is requested.
Safe checks you can make
- Read the full display and note A.02.06 exactly, including any other symbol or message.
- Look at the external pressure gauge without removing the boiler casing or touching pipework.
- Check whether the heating and hot-water cylinder are both affected.
- Look from a safe distance for obvious water around the boiler, radiators or exposed pipework.
- Note whether the warning appeared once or keeps returning after the appliance has cooled.
If water is close to electrical fittings, do not touch the boiler, controls or wet equipment. Keep people away from the area and seek professional help. If a ceiling is bulging or water is spreading rapidly, treat the leak as an urgent household problem.
Should you add water to the system?
Use only the instructions for your exact Baxi model and installation. The Baxi 800 System 2 product information identifies an external pressure gauge, but the arrangement used to restore pressure can differ between homes. Do not copy a generic online video, guess which valves to turn or force a stiff control.
If the official user guide for your exact appliance gives a permitted homeowner step, follow it once and stop if anything is unclear, the pressure changes unexpectedly or the warning remains. Repeatedly adding water is not a solution. It can hide an ongoing problem and makes the useful pattern harder for an engineer to assess.
Never open the boiler casing, disturb sealed parts or try to repair a leak yourself. Work on a gas boiler and its safety controls belongs with a suitably qualified Gas Safe registered engineer.
When the warning needs repair
Book an engineer when A.02.06 stays on, comes back, or is accompanied by repeated pressure loss. Repair is also appropriate when there is visible water, the gauge will not remain within the range stated in the model’s user guide, the system makes new noises, or heating and cylinder recovery are unreliable.
Do not keep resetting the boiler or repeatedly restoring pressure to get through another day. A temporary return to operation does not show that the underlying condition has gone away. The recurring pattern is useful evidence and should be shared with the engineer.
What to record before the visit
Take a clear photograph of the display and, separately, the pressure gauge. Note whether the system was cold or warm, the time the code appeared, what the thermostat was requesting and whether hot-water cylinder reheating was also due. Mention any recent radiator work, maintenance or visible water, but do not investigate inside the appliance.
These details help the engineer understand the sequence without you having to make unsafe checks. Keep access to the boiler and controls clear, and have the model details available if they can be read externally.
Low pressure and gas emergencies are different
A.02.06 is a heating-circuit pressure warning, not a carbon-monoxide alert. However, if you smell gas, suspect carbon monoxide, feel unwell around the appliance or a carbon-monoxide alarm sounds, do not continue ordinary fault-code checks. Turn off the appliance only if it is safe to do so, ventilate where possible, leave the property and follow current emergency advice from the Gas Emergency Service and Gas Safe Register.
Quick answers
What does Baxi A.02.06 mean?
Baxi defines A.02.06 as low system pressure in the heating circuit for the relevant Combi & System 2 boiler group.
Does A.02.06 prove there is a leak?
No. A leak is one possibility, but the code itself reports low pressure and does not confirm why it happened.
Can I keep using the boiler?
Do not rely on a boiler that repeatedly reports low pressure. Follow the exact user guide for safe user actions and arrange repair if the warning remains or returns.
Why can hot water be affected on a system boiler?
The Baxi 800 System 2 provides heat to a separate cylinder. If boiler operation is interrupted, the cylinder may not reheat as expected.
Should I reset it repeatedly?
No. Repeated resets can obscure a recurring fault pattern. Use only a permitted guide-directed reset once, if the exact user guide advises it, then seek help if the warning persists.
Need the boiler repaired?
Your boiler fault is fixed for the agreed price, subject to eligibility and terms.