D4 271 — Flow/safety sensor temperature difference exceeds limit

What does D4 271 mean?

The temperature difference between the flow and safety sensors has exceeded the permissible limit, or is too high. This is a safety measure to prevent overheating.

• Restricted water flow in the heating system.
• Faulty flow or safety temperature sensor.
• Pump malfunction or blockage.
• Accumulation of sludge or debris in the heat exchanger.

Click steps to track your progress.

1. 1

   Check your system pressure and top it up if necessary.

2. 2

   Ensure all radiator valves are fully open to allow for proper water circulation.

3. 3

   Reset the boiler. If the issue recurs, contact a Gas Safe registered engineer to check sensors and system flow.