154 High
Your boiler has detected that water is moving too slowly or in the wrong direction through the system, causing the pipes to heat up unevenly.
Technical description: Return greater than flow – flow temperature increases too fast
Typical repair cost: £120-450 (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 154 — no call-out fees, no surprises.
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Parts commonly replaced
- Central heating pump
- Flow/Return temperature sensors
- Diverter valve
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