Boiler Repairs

Basic trouble shooting and fixing simple errors


As professional Gas Safe Register installers for gas boilers, MP GAS AND PLUMBING are fully qualified and experienced to service, upgrade and repair all types of boiler, and carry out repairs to existing hot water and central heating systems.

It’s important to us that that we can always repair and maintain each and every type of boiler available on the market and ensure our customers have hot water and heating systems working at the peak of their efficiency.

To guarantee that we are always able to provide our customers with the highest standards of professional service and boiler care we constantly keep up with all the latest technical trouble-shooting advice and information.

Many of today’s modern systems are manufactured with on-board self-diagnostics, which supply fault light indicators or error codes to help owners and engineers to quickly find out the source of a problem and how it may be remedied.

Customers can often save time and money by being able to remedy a simple fault themselves or provide the information about a boiler problem if they can understand the fault indicator or error code when they first speak with a plumber over the telephone.

Worcester Greenstar Fault Codes:

Identifying a possible simple fault with a Worcester Greenstar boiler is made relatively straightforward because of the internal diagnosis system.


COMBI BOILERS – Greenstar 24i/28i Junior

BLUE LIGHT INDICATOR                               LOCKOUT RESET BUTTON                                    FAULT

OFF                                                             OFF                                                   No power at control board


ON                                                              OFF                                                   Not operating during demand for central heating / hot                                                                                                                                          water / any demand.Operating without live demand at ST10-LR.

Slow Flash                                                   Flashing (reset required)                      Ignition lockout. Flue overheating. Heat exchanger overheating.


Fast flash                                                    OFF                                                    Volatile lockout


Fast flash                                                    Flashing                                              Internal fault


2 pulses                                                      No light                                              Not a fault code


5 pulses                                                      No light                                              Not a fault code



REGULAR GAS BOILERS – Greenstar 12Ri /15Ri / 18Ri /24Ri


SYSTEM GAS BOILERS – Greenstar 12i /15i /18i /24i


A fault occurring with a Greenstar Ri boiler is identified by the reset button flashing once per second and the mains indicator (blue light), which also will flash but at different speeds according to the type of fault.


PROBLEM                                                                                       CAUSE


Desired room temperature not reached.                                      Thermostatic radiator value or values or room thermostat set too low. Temperature                                                                                                  control for CH flow on boiler set too low. Air trapped in heating system.


Desired room temperature exceeded by large amount.                 Radiators too hot.


Heating stays on for too long.                                                    Programmer is incorrectly set.


No on/off indicator light.                                                           Brief power failure.


Fast flash                                                                                Brief power failure.


Hot water temperature too low.                                                Programmer setting. Cylinder thermostat set too low.


Hot water temperature too high.                                               Cylinder thermostat set too high.


Please Note: If your Worcester Bosch boiler model is not featured in the above examples or if a fault remains and cannot be cleared by pressing the reset button, then you will need to call an accredited, qualified Worcester Bosch service engineer, such as BBS Plumbing and Heating, and provide a description of the fault and, if possible the fault flashing sequence from the flashing indicators.

MP Gas and Plumbing,

15 Holden gardens


SS14 3LF

Phone : 07894994021


Gas Safe Register Nr. 588980

Gas Safe Register is the official list of gas engineers who are registered to work safely and legally on gas appliances having replaced CORGI registration. Visit the website to learn more:

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