How much does it cost to fix Remeha error code 20-21?

Typical repair cost for the Remeha 20-21 fault is £180-450 including labour.

20-21 High

Remeha 20-21 Fault Code

Q: What does the Remeha 20-21 fault code mean?

Your boiler has shut down because it has detected internal temperatures that are too high, triggered by a safety sensor to prevent overheating.

Also written as 2021 — same fault.

The Remeha 20-21 fault code means: your boiler has shut down because it has detected internal temperatures that are too high, triggered by a safety sensor to prevent overheating.. It appears on 3 Remeha models in our database.

Technical description: High limit stat

What causes the Remeha 20-21 fault?

This fault occurs when the boiler's internal water temperature exceeds safe operating limits, causing a safety sensor to trip and shut the system down. The most common reasons are a pump failure that stops water from moving or a buildup of limescale and sludge that restricts flow through the heat exchanger. Essentially, heat is being generated faster than the water can carry it away to your radiators.

This fault is more common in autumn when heating systems are turned on for the first time after summer, as circulation pumps can seize during long periods of inactivity.

Typical repair cost £180-450 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Remeha models that show the 20-21 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Remeha 20-21 fault code information on this page is sourced and cross-checked against the official Remeha service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026