Worcester Bosch WR325 RSF Fault codes & diagnostics

67 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Combi Natural GasLPG 24 kW 1994-2000 Discontinued
GC Number 47-311-20

Replaced by: Greenstar i Junior

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Severity at a glance

Each cell = one fault code. Hover to identify.
3 Emergency 57 High 3 Medium 4 Low

All 67 documented codes

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10

Your boiler is failing to detect that water is circulating correctly, which is preventing it from firing up to provide your heating or hot water.

High Engineer only £150-250

Parts commonly replaced

  • Flow sensor
  • Diverter valve actuator

Related codes

12

Your boiler is failing to ignite or detect a flame, meaning your heating and hot water have stopped working.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame rectification probe

Related codes

14

Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage or danger.

High Engineer only £120-250

Parts commonly replaced

  • Limit thermostat
  • Pump
  • Diverter valve
  • Heat exchanger

Related codes

15

Your boiler is failing to detect the incoming electrical signal it needs to start or continue its heating cycle.

High Engineer only £120-250

Parts commonly replaced

  • Flow switch
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

18

Your boiler is failing to light the flame needed to produce heat or hot water and has automatically shut down for your safety.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Ignition lead
  • Printed Circuit Board (PCB)

Related codes

19

Your boiler is struggling to detect the water flow correctly, preventing it from switching on your heating or hot water safely.

High Engineer only £150-250

Parts commonly replaced

  • Flow switch
  • Microswitch
  • Wiring harness

Related codes

28

Your boiler is struggling to communicate with your wall-mounted thermostat, which is currently preventing the heating from turning on.

Medium Engineer only £120-250

Parts commonly replaced

  • External thermostat
  • Control module PCB
  • Wiring harness
54

Your boiler has reached an unsafe temperature and has shut itself down to prevent damage to the internal components.

High DIY-safe £120-350

What to check first

  1. Check if any radiator valves have been accidentally closed and open them fully
  2. Ensure your system pressure is between 1 and 1.5 bar on the pressure gauge
  3. Gently bleed your radiators to remove any trapped air that might be blocking water flow

Parts commonly replaced

  • Circulating pump
  • Overheat thermostat
  • Heat exchanger cleaning/replacement

Related codes

62

Your boiler is failing to detect that water is moving through the system, which is preventing it from safely firing up.

High Engineer only £180-350

Parts commonly replaced

  • Flow sensor
  • Microswitch
  • PCB
Showing 11–20 of 67
65

Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.

High Engineer only £120-250

Parts commonly replaced

  • Limit thermostat
  • Pump
  • Diverter valve
  • Heat exchanger

Related codes

66C

Your boiler has stopped working because it cannot confirm that the fan is safely pushing exhaust fumes out of the flue.

High Engineer only £120-280

Parts commonly replaced

  • Air pressure switch
  • Fan assembly
  • Venturi tube

Related codes

69

Your boiler is struggling to detect water moving through the system, which is preventing it from safely turning on your heating or hot water.

High Engineer only £150-250

Parts commonly replaced

  • Flow sensor
  • Microswitch
  • Diverter valve diaphragm

Related codes

112

Your boiler has lost the ability to accurately measure the temperature of the water returning to it, so it has stopped working as a safety precaution.

High Engineer only £120-220

Parts commonly replaced

  • Return NTC sensor
  • Wiring harness
114

Your boiler is failing to ignite the flame reliably, meaning it cannot produce heat or hot water.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Ignition lead
  • Printed Circuit Board

Related codes

115

Your boiler is struggling to detect or control the flow of gas required to ignite the flame, meaning it cannot currently produce hot water or heating.

High Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • PCB

Related codes

116

Your boiler's water flow control mechanism is experiencing a communication error, which prevents it from properly managing the flow of hot water to your taps or radiators.

High Engineer only £180-350

Parts commonly replaced

  • Diverter valve
  • Actuator motor
  • PCB
119

Your boiler is struggling to detect the flame needed to heat your water, which is causing it to shut down for safety reasons.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Flame rectification probe
  • Ignition lead

Related codes

144

Your boiler has detected that the water temperature is rising too quickly while the burner is on, so it has stopped heating to prevent damage.

High Engineer only £150-300

Parts commonly replaced

  • NTC temperature sensor
  • Central heating pump
  • Heat exchanger
660

Your boiler has detected an electrical fault within its internal wiring or a control component, causing it to shut down for safety.

High Engineer only £140-350

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Internal Wiring Harness
  • External Controls Interface

Related codes

Showing 21–30 of 67
661

Your boiler is not receiving the correct electrical voltage needed to run, likely due to an issue with your home's power supply or a failing internal circuit board.

High Engineer only £120-£350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Transformer

Related codes

662

Your boiler is failing to start up because the internal computer responsible for lighting the flame has encountered a fault.

High Engineer only £250-£450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Ignition electrodes
  • Wiring harness

Related codes

668

Your boiler has stopped working because the internal fan, which safely exhausts fumes, is not running correctly.

High Engineer only £280-550

Parts commonly replaced

  • Fan Assembly
  • Air Pressure Switch
  • Main Control Board

Related codes

669

Your boiler has stopped working because it cannot safely clear waste gases through the flue pipe.

High Engineer only £120-£350

Parts commonly replaced

  • Fan assembly
  • Air pressure switch
  • Venturi tube

Related codes

A1

Your boiler has detected that a internal sensor responsible for measuring water temperature has stopped working correctly.

High Engineer only £90-160

Parts commonly replaced

  • NTC Thermistor
  • Temperature Sensor
  • Wiring Harness

Related codes

A2

Your boiler has detected an issue with the air supply or the way it releases exhaust gases, preventing it from firing up safely.

High Engineer only £120-350

Parts commonly replaced

  • Fan
  • Air pressure switch
  • Flue seals

Related codes

A4

Your boiler has detected an issue with the air flow or the internal fan that clears away waste gases.

High Engineer only £120-450

Parts commonly replaced

  • Fan assembly
  • Air pressure switch
  • Flue venting components

Related codes

A5

Your boiler has detected an electrical communication problem with its internal control system which is preventing it from firing up.

High Engineer only £180-350

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

A7

Your boiler is struggling to accurately measure the temperature of the water being heated for your taps and showers.

Medium Engineer only £120-200

Parts commonly replaced

  • Hot water NTC sensor
  • Wiring harness

Related codes

A8

Your boiler has lost its internal connection between the main control board and the display panel, meaning it cannot communicate with itself properly.

High Engineer only £180-£450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Internal Ribbon Cable
  • Display Interface

Related codes

Showing 31–40 of 67
A9

Your boiler is struggling to correctly flow water through the system, which is preventing it from heating up properly.

High Engineer only £120-£250

Parts commonly replaced

  • Diverter Valve Diaphragm
  • Diverter Valve Assembly
  • Flow Sensor

Related codes

AC

Your boiler has lost communication between its internal computer and a key electrical sensor or motor, meaning it cannot operate safely.

High Engineer only £120-450

Parts commonly replaced

  • Wiring harness
  • Main PCB
  • NTC Sensor

Related codes

Ad

Your boiler is having trouble communicating with the sensor that monitors the temperature of your hot water cylinder.

High Engineer only £90-180

Parts commonly replaced

  • Cylinder NTC sensor
  • Wiring harness

Related codes

b1

Your boiler has lost its connection to its internal memory chip, meaning it no longer knows its specific configuration settings.

High Engineer only £120-280

Parts commonly replaced

  • Code plug
  • Printed Circuit Board (PCB)

Related codes

C0

Your boiler is having trouble controlling the flow of water through the system, which is likely affecting your hot water or heating performance.

High Engineer only £180-350

Parts commonly replaced

  • Flow regulation valve
  • Motorised valve actuator
  • Main PCB

Related codes

C1

Your boiler has stopped working because it cannot safely confirm that the fan is pushing exhaust fumes out of the flue.

High Engineer only £120-280

Parts commonly replaced

  • Air Pressure Switch
  • Fan Assembly
  • Venturi Tube

Related codes

C2

Your boiler has detected a problem with the way gas is being supplied or ignited at the burner, preventing it from heating your water.

High Engineer only £120-350

Parts commonly replaced

  • Gas valve
  • Burner assembly
  • Ignition electrodes

Related codes

C4

Your boiler has detected an issue with the air pressure inside the system, which is stopping it from safely starting the burner.

High Engineer only £120-280

Parts commonly replaced

  • Air pressure switch
  • Fan assembly
  • Venturi tube

Related codes

C6

Your boiler's fan is not running at the correct speed or has stopped working entirely, which means the system cannot safely clear exhaust fumes and has shut down as a precaution.

High Engineer only £200-£450

Parts commonly replaced

  • Fan assembly
  • Air pressure switch
  • Main PCB

Related codes

d3

Your boiler has lost the signal from a required safety link or bridge, meaning it cannot safely start its ignition process.

High Engineer only £120-250

Parts commonly replaced

  • Control board
  • Wiring loom
  • Link bridge (terminal block)

Related codes

Showing 41–50 of 67
E2

Your boiler has stopped working because it cannot correctly measure the temperature of the water leaving the unit.

High Engineer only £90-160

Parts commonly replaced

  • Flow temperature sensor (NTC thermistor)
  • Wiring harness connecting the sensor

Related codes

E4

Your boiler has detected a problem with how it controls the gas flow, meaning it cannot safely regulate the flame and has shut down as a precaution.

High Engineer only £160-£320

Parts commonly replaced

  • Gas Valve
  • Modulator Coil
  • Printed Circuit Board (PCB)

Related codes

E5

Your boiler is failing to detect a flame after it tries to ignite, causing it to shut down for safety.

High Engineer only £120-280

Parts commonly replaced

  • Ionisation electrode
  • Flame sensing lead
  • Printed Circuit Board (PCB)

Related codes

E9

Your boiler has sensed it is getting too hot and has shut itself down as a safety precaution.

High DIY-safe £90-180

What to check first

  1. Check that your radiator valves are open and not turned off
  2. Ensure there is enough water pressure in the system by checking the pressure gauge
  3. Press the reset button on the front of the boiler control panel

Parts commonly replaced

  • Overheat Thermostat (STB)
  • Circulation Pump
  • Temperature Sensor (NTC)

Related codes

E44

Your boiler has detected that there is too much water in the system combined with high temperatures, causing it to shut down for safety.

High DIY-safe £80-180

What to check first

  1. Check that the internal or external filling loop valves are fully closed.
  2. Bled water from a radiator bleed valve to reduce the system pressure.
  3. Monitor the pressure gauge to ensure it stays between 1.0 and 1.5 bar when cold.
  4. If pressure rises again without intervention, contact a Gas Safe engineer.

Parts commonly replaced

  • Filling loop valve
  • Expansion vessel
  • Pressure relief valve

Related codes

EA

Your boiler is failing to light the burner, meaning it cannot provide you with any hot water or heating.

High Engineer only £150-300

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Ionisation probe
  • PCB
EE2

Your boiler has detected that a temperature sensor is giving readings outside of its normal bounds, causing the system to shut down as a precaution.

High Engineer only £120-£220

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring Harness
  • Main PCB

Related codes

EE4

Your boiler is struggling to spark or stay lit, which means your heating and hot water have stopped working.

High Engineer only £100-£220

Parts commonly replaced

  • Ignition electrodes
  • Lead set
  • Ignition transformer

Related codes

EE5

Your boiler's gas valve is not opening or functioning correctly, preventing the system from producing heat or hot water.

High Engineer only £220-£380

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

EE6

Your boiler has detected an issue with the external valve system, preventing it from operating correctly and resulting in a total loss of heating and hot water.

High Engineer only £180-350

Parts commonly replaced

  • External zone valve
  • Motorised valve head
  • Wiring center

Related codes

Showing 51–60 of 67
EE9

Your boiler has detected a communication issue or a fault with one of its internal ignition electrodes, meaning it cannot safely light the burner.

High Engineer only £120-£240

Parts commonly replaced

  • Ignition Electrode
  • Flame Sensing Electrode
  • Ignition Lead
  • Control Board

Related codes

Explosive ignition

Your boiler is struggling to light smoothly, causing it to build up a small amount of gas before igniting with a loud bang.

Emergency Engineer only £150-300

Parts commonly replaced

  • Pilot burner assembly
  • Gas valve
  • Ignition electrode
F0

Your boiler has detected a critical internal software or electronic processing failure and has stopped working as a safety precaution.

High Engineer only £200-450

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

F7

Your boiler is detecting a flame inside its internal chamber when the burner should be completely turned off.

Emergency Engineer only £150-350

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)
  • Flame rectification electrode

Related codes

FA

Your boiler has detected that the burner flame is still lit even after it has tried to turn the gas supply off, which indicates a serious safety malfunction.

Emergency Engineer only £150-300

Parts commonly replaced

  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

FC

Your boiler's electronic control panel is not communicating with the main computer system, preventing the boiler from receiving instructions to heat your home.

High Engineer only £150-350

Parts commonly replaced

  • Control unit
  • Wiring harness
  • Display fascia

Related codes

Fd

Your boiler's reset function has been triggered inadvertently, meaning it just needs to be restarted to resume normal operation.

Low DIY-safe

What to check first

  1. Locate the reset button on the front control panel.
  2. Press and hold the button for 2 to 5 seconds.
  3. Wait a few minutes for the boiler to complete its restart sequence.
G2

Your boiler has detected an issue with the cold water arriving at the unit, meaning it cannot safely heat water for your taps or shower.

High DIY-safe £90-180

What to check first

  1. Check that the main water stopcock in your home is fully open.
  2. Ensure any isolation valves on the pipework leading to the boiler are turned to the 'on' position.
  3. Check with your local water provider to see if there is a supply outage or burst pipe in your area.

Parts commonly replaced

  • Inlet water filter
  • Inlet pressure sensor
  • Flow turbine

Related codes

G5

Your boiler has failed to ignite or stay lit correctly, meaning it cannot provide heating or hot water until it is reset or repaired.

High Engineer only £120-350

Parts commonly replaced

  • Ionisation probe
  • Ignition electrode
  • Gas valve
  • PCB

Related codes

G9

Your boiler has detected that hot water is escaping through the safety overflow pipe, usually because the system is overheating or a valve has failed.

High Engineer only £120-280

Parts commonly replaced

  • Pressure Relief Valve (PRV)
  • Expansion Vessel
  • Temperature Sensor

Related codes

Showing 61–67 of 67
H8

Your boiler is undergoing a manual reset process and should return to normal operation shortly unless a repeat fault occurs.

Low DIY-safe

What to check first

  1. Wait approximately 30 seconds for the reset sequence to complete
  2. Ensure the reset button was pressed firmly if the code persists
  3. Monitor the boiler for any new fault codes after the reset finishes

Related codes

Incorrect water flow rate

Your boiler is struggling to detect the flow of water needed to heat your taps, usually because the incoming water supply is restricted or a internal sensor is stuck.

High DIY-safe £120-250

What to check first

  1. Check that the isolation valve on the cold water mains pipe leading to your boiler is fully open.
  2. Check all taps in your home to ensure you have normal mains water pressure.
  3. Restart the boiler using the reset button to see if it clears the temporary fault.

Parts commonly replaced

  • Water section diaphragm
  • Flow switch
  • Microswitch
Incorrect water temperature

Your boiler is struggling to control the temperature of the water, which means it cannot reliably provide hot water or heating.

High Engineer only £150-300

Parts commonly replaced

  • Water diaphragm
  • Gas valve
  • NTC sensor

Related codes

Main burner will not light

Your boiler is failing to ignite the flame needed to heat your water, which could be caused by blocked gas flow or a worn internal component.

High Engineer only £150-350

Parts commonly replaced

  • Water section diaphragm
  • Gas valve
  • Microswitch
Noise

Your boiler is struggling to pass water through its heating system, which is causing it to make loud, rumbling, or banging noises.

Medium Engineer only £150-350

Parts commonly replaced

  • Heat exchanger
  • Pump
  • Diverter valve

Related codes

P8

Your boiler has detected that the water pressure inside the system is too high, which can cause safety valves to leak or the unit to shut down.

High DIY-safe £90-220

What to check first

  1. Check that the filling loop valves are fully closed
  2. Bleed a radiator to release excess water pressure
  3. Monitor the pressure gauge stays between 1 and 1.5 bar
  4. Ensure the pressure relief valve is not dripping outside

Parts commonly replaced

  • Pressure Relief Valve (PRV)
  • Expansion Vessel
  • Filling Loop