How much does it cost to fix Johnson Starley error code E18?

Typical repair cost for the Johnson Starley E18 fault is £120-220 including labour.

E18 High

Johnson Starley E18 Fault Code

Q: What does the Johnson Starley E18 fault code mean?

Your boiler has stopped working because the waste water produced during heating cannot drain away correctly, usually due to a blocked or faulty pump.

The Johnson Starley E18 fault code means: your boiler has stopped working because the waste water produced during heating cannot drain away correctly, usually due to a blocked or faulty pump.. It appears on 2 Johnson Starley models in our database.

Technical description: Condensate pump / Water level fault

Typical repair cost £120-220 (including labour)

DIY fix possible

Check the external white plastic drainage pipe for any signs of freezing or blockages.Ensure any flexible hoses connected to the condensate pump are not kinked or trapped.If the outlet pipe is frozen, gently pour warm (not boiling) water over the pipe to thaw it.

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Johnson Starley models that show the E18 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Johnson Starley E18 fault code information on this page is sourced and cross-checked against the official Johnson Starley service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026