BoilerFaultCodesYour boiler has shut down because it thinks the water returning from your radiators is hotter than the water leaving the boiler, which suggests a sensor error or a circulation problem.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Return temperature higher than flow temperature
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the water coming back from your heating system is hotter than the water it just sent out, which is physically impossible during normal operation. The most common reason is that one of the temperature sensors has failed or 'drifted' out of calibration, though it can also be triggered by a pump failure or a significant blockage that has completely stopped water from circulating.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E15 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Remeha Quinta 115 is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.