The Baxi A.00.29 code means the solar temperature sensor is either shorted or measures a temperature above range. It is a sensor-related warning on compatible Baxi Combi 2 and System 2 controls. It does not, by itself, prove that the sensor is the only part needing attention.
What does Baxi code A.00.29 mean?
Baxi lists A.00.29 as: “Solar temperature sensor is either shorted or measures a temperature above range.” In plain English, the boiler control is receiving a solar-temperature signal that is outside the value it expects at the high end.
The wording covers more than one possibility. The reading may relate to the sensor, its connection, the way the system has been configured, or the wider solar-thermal control arrangement. The code alone cannot tell a homeowner which of those applies, so replacing a part on the strength of the display would be guesswork.
Which Baxi boilers can show A.00.29?
Baxi currently includes A.00.29 in the error-code group for these ranges:
- Baxi 200 Combi 2
- Baxi 400 Combi 2
- Baxi 600 Combi 2
- Baxi 800 Combi 2
- Baxi Assure 500 Combi 2
- Baxi 600 System 2
- Baxi 800 System 2
- Baxi Assure 500 System 2
That list does not mean every installation has a solar-temperature sensor. The code is relevant where the configured heating or hot-water system expects one. A solar-thermal system uses heat from roof collectors to help warm stored water; it is different from solar photovoltaic panels, which generate electricity.
Can hot sunshine cause the code?
Do not assume that a sunny day or warm roof alone explains A.00.29. “Above range” refers to the signal seen by the control, not simply to normal summer weather. If the code appears, the system details and exact sensor circuit need checking by a competent professional.
What can you safely check?
You can collect useful information without removing a cover or touching electrical parts:
- Write down the exact code, including the dots and leading zeros.
- Check the boiler model name on the outside of the appliance or in its paperwork.
- Look for paperwork showing whether the property has a solar-thermal cylinder or solar hot-water controls.
- Note whether central heating and hot water are working normally.
- Record any other code shown before or after A.00.29.
- Tell the engineer about recent work on the solar-thermal system, cylinder, controls or electrical supply.
Do not climb onto the roof, open a solar controller, test wiring, measure resistance, alter configuration settings or remove the boiler casing. Those checks belong with someone who has the right equipment and product knowledge.
Should you reset the boiler?
Use only the instructions for your exact Baxi model. If its user guide permits a homeowner reset for this situation, one attempt is enough. Repeated resetting can hide the sequence of events and will not correct an out-of-range signal. If the code remains or returns, arrange a repair.
When should you book a repair?
Book a professional repair when A.00.29 stays on the display, comes back after the one permitted reset, or is accompanied by loss of heating or hot water. Give the engineer the full model, the exact code and details of any solar-thermal equipment. That helps the right system be assessed without assuming the fault is confined to one component.
If stored water seems dangerously hot, a cylinder is leaking, or there is any immediate risk of scalding, stop using the affected hot-water outlet and seek urgent professional help.
Keep the job safe
A boiler and its associated controls combine electricity, hot water and—in a gas appliance—gas combustion. Do not remove the casing or attempt electrical or gas work yourself. Gas-appliance work must be carried out by an appropriately qualified Gas Safe registered engineer.
For more homeowner-safe explanations, visit our boiler help guides.
Want the A.00.29 fault dealt with?
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Quick answers about Baxi A.00.29
What is the Baxi A.00.29 fault code?
It means the solar temperature sensor is either shorted or measures a temperature above range.
Is A.00.29 a solar-panel fault?
It relates to the solar-temperature input expected by a compatible solar-thermal arrangement. It does not refer to ordinary photovoltaic electricity panels.
Does every Baxi Combi 2 or System 2 have a solar sensor?
No. The code is relevant only where the configured installation expects that sensor or related solar-thermal control.
Can I test the solar sensor myself?
No. Do not open controls, test wiring, change settings or remove the boiler casing. Record the code and arrange professional help.
Will resetting clear Baxi A.00.29?
Follow the exact model’s user guide. If it allows a reset, try it once only. A code that stays or returns needs professional attention.