Bosch Thermotechnology · Error codes
Buderus GB162 A01 828 — Water Pressure Indication of the Heating System Does not Work
A01 828
Water pressure indication of the heating system does not work. The water pressure indication of the heating system does not work, so there is no heating operation and no DHW. The table classifies it as Blocking fault code, reset required no, UBA3 LED off.
Applies to
This low-water or pressure protection code is displayed by the UBA3 control (display codes and LED flags) on Buderus GB162 models (80–200), as documented in Buderus GB162 Service Instructions, doc 6720614965_05 (6720614965_05). Codes can differ between controller generations, so always check the manual that matches your unit.
Controller: UBA3 control (display codes and LED flags). Source manual: 6720614965_05 (2012-11).
Why a code is not a diagnosis
A water-pressure or low-water code can mean a genuine leak or empty system, a failed expansion tank, a faulty fill valve, or a sensor problem. The appliance does not distinguish these.
Safe things to observe
- Read the pressure gauge and compare it with the normal cold-system pressure your installer set.
- Look for drips or wet spots near the appliance, pipes and the relief-valve discharge.
Do not
- Do not keep re-pressurizing a system that keeps losing water.
- Do not cap a relief-valve discharge pipe.
How professional service helps
- A technician finds and repairs the leak, checks the expansion tank and fill assembly, and verifies the sensor circuit.
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Frequently asked questions
Can I clear this code myself?
Clearing a code without fixing its cause usually just brings it back. Note the code, check the safe items on this page, then call a licensed technician. If your appliance manual describes a user reset for this exact code and it stays away, no call may be needed.
Boiler locked out? Call with the alert text ready.
The brand, model and this alert are passed along when you request service online, so the technician arrives prepared.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
- Buderus GB162 Service Instructions, doc 6720614965_05 · 6720614965_05 · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.