Bosch Thermotechnology · Error codes
Buderus GB162 A11 816 — No Communication with the Rc35 Takes Place
A11 816
No communication with the RC35 takes place. No communication with the RC35 takes place, so no reset is required and the UBA 3 LED is off. The table classifies it as Blocking fault code, reset required no, UBA3 LED off.
Applies to
This communication or network fault 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 communication code involves the link between controls (cascade, remote, sensors on a bus). Another unit being off, a wiring fault or an address conflict can all produce it.
Safe things to observe
- Check that every appliance in a multi-unit plant has power.
- Report the code together with any other codes on the system.
Do not
- Do not re-address or rewire control networks yourself.
How professional service helps
- A technician verifies power, wiring and settings across the connected units.
- Combustion and safety devices are verified with an analyser and the manufacturer's procedure after any repair.
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.