ER 19 Medium

Johnson Starley ER 19 Fault Code

Also written as ER19 — same fault.

The Johnson Starley ER 19 fault code means: your boiler is struggling to accurately measure the temperature of the incoming cold water, which may cause your hot water to be inconsistent or unavailable.. It appears on 1 Johnson Starley model in our database.

Book a service

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: DHW inlet probe fault
Typical repair cost £120-220 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Johnson Starley models that show the ER 19 fault code

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

Source

Johnson Starley ER 19 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 7 July 2026