BoilerFaultCodesYour boiler has detected a fault with a temperature sensor that monitors the water sent to your radiators, meaning it cannot safely regulate your heating.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: CH flow NTC sensor defective.
What causes this fault?
This fault occurs when the internal sensor responsible for tracking the temperature of water leaving the boiler fails to send a reliable signal to the main control board. The most common reason is that the sensor's internal components have worn out over time or a loose electrical connection has developed within the wiring harness. Because the boiler no longer knows how hot the water is, it shuts down as a safety precaution to prevent overheating.
This fault often appears at the start of autumn when the heating system is first turned on after being idle all summer, which can stress aging electronic components.
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 E2 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Worcester Bosch RD 532i RD 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.