BoilerFaultCodesDimplex 42 Fault Code
The Dimplex 42 fault code means: your boiler has detected that there is not enough water flowing through the system or there is insufficient water pressure to operate safely.. It appears on 2 Dimplex models in our database.
Technical description: Water flow failure/ Flame for a short period only - Low water pressure / No flow / Dry run protection
DIY fix possible
Check the pressure gauge on the front of the boiler; it should ideally be between 1.0 and 1.5 bar.If the pressure is below 1.0, use the external filling loop to top up the system with water until the gauge reaches 1.2 bar.Ensure all radiator valves are open and that the pump is not making loud grinding noises.Reset the boiler to clear the fault code once the pressure is restored.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like 42: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Dimplex models that show the 42 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Dimplex 42 fault code information on this page is sourced and cross-checked against the official Dimplex service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026