E42 High
Your boiler has detected that heat is not moving through the system correctly, usually meaning the water is hotter in one part of the machine than another.
Technical description: Different temperature error
Typical repair cost: £120-£350 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Protect yourself from future repair bills
A boiler cover plan would cover faults like E42 — no call-out fees, no surprises.
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Parts commonly replaced
- Temperature sensors (NTC thermistors)
- Circulation pump
- Heat exchanger
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