Buderus 0Y 276 error (flow overheating) — causes and fix

The error code 0Y 276 on your Buderus boiler indicates an overheating event on the flow (primary) circuit. The sub-code 276 identifies the sensor that raised the alarm. The boiler locks out to protect the primary heat exchanger from boiling or damage.

What does 0Y 276 mean?

Code 0Y 276 flags that the flow sensor has detected a temperature spike on the primary heating circuit above the safety threshold (typically 95°C). The boiler cuts the gas immediately.

Symptoms

• Boiler stopped, cannot restart immediately
• No heating, sometimes no DHW (depending on model)
• Just before lockout: radiators very hot, then suddenly cold
• Boiling/gurgling sound inside the heat exchanger
• Occasional faint smell of « hot metal » near the boiler

Affected Buderus models

• Buderus Logamax Plus GB125 (very common, especially after 8–10 years)
• Buderus Logamax Plus GB132
• Buderus Logamax Plus GB172
• Buderus Logano G125 / G215 (configuration-dependent)

Common causes

• Insufficient water circulation — seized or weakening pump, partial sludge blockage (40% of cases)
• Misreading flow sensor — returning a false high value
• Too many radiators closed — water can’t flow freely
• Faulty expansion vessel — unstable pressure disrupting circulation
• Sludge in primary heat exchanger — thermal insulation, local overheating

Related variants

0Y alone — generic flow overheating fault.
0Y 276 — most common variant, main flow sensor.
0Y 359 — DHW-side variant, domestic hot water overheating.

Before calling a professional

1. Let the boiler cool for at least 30 minutes
2. Check that not all radiators are closed simultaneously
3. Check the pressure gauge reads 1.2–1.8 bar when cold
4. Listen for the circulation pump at restart — a normal, steady hum
5. Note whether the fault returns quickly or only under heavy heating demand

Never force repeated restarts. Repeated overheating damages the heat exchanger and can cause a costly internal leak.

Intervention costs in Luxembourg

• Diagnosis + unlock: on request
• Complete heating-system flush (power-flush): on request depending on install size
• Primary pump replacement: on request
• Flow sensor replacement: on request

Frequently asked questions

Is it dangerous to restart the boiler?

The 0Y 276 code is a safety that has already acted. A single restart after the boiler cools is possible, but if the fault returns within 24–48 hours, professional intervention is required.

Does a power-flush always fix the problem?

In roughly 60% of cases if the boiler is over 8 years old and has never been flushed. If the fault persists after flushing, the pump or flow sensor is the cause.

How long can I wait to fix this?

In winter, not more than 24–48 hours (risk of circuit freezing). Outside heating season, a few days is acceptable.

Need an English-speaking heating engineer in Luxembourg?

Weber & Fils is certified on all Buderus boilers in Luxembourg (Logamax Plus GB125, GB132, Logano G125) and stocks the most common parts. Their technicians speak English fluently.

For quotes and emergency call-outs: weberetfils.lu/en or call +352 20 60 22 22 — 24/7.

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