BoilerFaultCodesYour boiler has detected a problem with the sensor that monitors hot water temperature, meaning you will likely have no hot water or inconsistent temperatures.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Domestic hot water (DHW) sensor damaged
What causes this fault?
This fault occurs when the internal sensor responsible for measuring the temperature of your hot water fails or sends an incorrect signal to the boiler’s control board. The most common reason is that the sensor has either burnt out over time or developed a lime-scale build-up that prevents it from reading the water temperature accurately.
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 E04 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Ravenheat CS 80/90, WH System, WH 80/90 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.