Common problems guide

The most common Dimplex boiler problems

The faults we see most often across the Dimplex range — with plain-English causes, what to check first, estimated repair costs, and whether it's a DIY job or needs a Gas Safe engineer. Based on fault-code data across 3 Dimplex boiler models.

33 unique codes
3 models covered
8 DIY-safe (top 8)
8 engineer needed

The most common Dimplex faults

01
1 High DIY-safe

Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.

What to try first

Check that all radiator valves are fully openEnsure the boiler pressure is between 1 and 1.5 barPress the reset button on the front control panelCheck for any visible leaks around the pipework

Est. cost
£90-280
Parts
Circulation pump, Overheat thermostat, Thermistor (NTC sensor)
Full guide for OV 32 1
02
4 High DIY-safe

Your boiler is trying to start up but cannot light the gas flame needed to provide heat and hot water.

What to try first

Check if other gas appliances, like a cooker, are working to ensure gas is reaching the propertyVerify that your gas cupboard valves are open or that you have credit on your meterPress the Reset button on the boiler control panel once to see if the system restarts

Est. cost
£120-350
Parts
Ignition Electrode, Gas Valve, Flame Sensing Probe
Full guide for Combi 38 4
03
5 High DIY-safe

Your boiler has started to heat up but the flame has unexpectedly gone out, causing the system to shut down for safety.

What to try first

Check that your gas emergency control valve is open and you have credit on your gas meterCheck if other gas appliances in your home, such as a hob, are working correctlyReset the boiler by following the instructions in your user manual

Est. cost
£120-350
Parts
Flame sensing electrode, Gas valve, Ignition lead
Full guide for Combi 38 5
04
6 High DIY-safe

Your boiler has shut down because the internal water temperature has become too hot.

What to try first

Check that all radiator valves are fully openEnsure the boiler pressure is between 1 and 1.5 barPress the reset button and wait for the boiler to restart

Est. cost
£100-£350
Parts
Circulating pump, NTC thermistor, Main heat exchanger
Full guide for System 30 6
05
32 High DIY-safe

Your boiler has stopped working because it cannot detect a flame or has lost its electrical connection, meaning you currently have no heating or hot water.

What to try first

Check if other gas appliances, like a hob, are working to ensure gas supply is activeEnsure the boiler is plugged in and the fused spur switch is turned onCheck your consumer unit/fuse box for any tripped switchesPress the Reset button on the boiler control panel

Est. cost
£120-350
Parts
Ignition electrode, Gas valve, Printed Circuit Board (PCB)
Full guide for Combi 38 32
06
41 High DIY-safe

Your boiler is struggling to circulate water properly, causing it to shut down shortly after it lights.

What to try first

Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.If the pressure is too low, use the filling loop to top it up.Ensure all radiator valves and external isolation valves are fully open.

Est. cost
£80-250
Parts
Circulation pump, Flow temperature sensor, Return temperature sensor
Full guide for Combi 38 41
07
42 High DIY-safe

Your boiler has detected that there is not enough water flowing through the system or there is insufficient water pressure to operate safely.

What to try first

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.

Est. cost
£80-250
Parts
Filling loop, Circulating pump, Water pressure switch
Full guide for Combi 38 42
08
(No display) High DIY-safe

Your boiler has no power and the screen is blank, meaning it cannot operate at all to provide heating or hot water.

What to try first

Check if the boiler's power switch is turned onCheck your home's main fuse box (RCD) to see if a circuit has trippedCheck the fuse in the boiler's fused spur switch (the wall switch near the boiler)

Est. cost
£80-250
Parts
Internal Glass Fuse, Printed Circuit Board (PCB), Transformer
Full guide for Combi 38 (No display)

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