Worcester Bosch R30 HE Plus Fault codes & diagnostics

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

Combi Natural Gas 35-40 kW 2005 onwards Discontinued
GC Number 47-311-79

Replaced by: Greenstar i System

Download the Worcester Bosch R30 HE Plus manualThe official installation and service manual (PDF), the document these fault codes were read from. PDF

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Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 11 High 1 Medium 1 Low
Just want the most common Worcester Bosch R30 HE Plus faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 14 documented codes

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A1

Your boiler has detected that there is not enough water circulating through the system to operate safely.

High DIY-safe £60-120

What to check first

  1. Check your boiler's pressure gauge to see if it is below 1 bar
  2. Locate the filling loop (usually silver braided hoses under the boiler)
  3. Slowly open the valves until the pressure reaches 1.5 bar, then close them tightly

Parts commonly replaced

  • Filling loop
  • Expansion vessel recharge
  • Internal pump

Related codes

Full explanation for A1
A7

Your boiler's temperature sensor for hot water has stopped working properly, meaning your taps may only provide cold or lukewarm water.

Medium Engineer only £90-160

Parts commonly replaced

  • Hot water NTC sensor
  • Connecting lead/wiring

Related codes

Full explanation for A7
A8

Your boiler's internal computer has lost contact with its control panel or external sensors, meaning it cannot receive the instructions it needs to work.

High Engineer only £150-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Display Interface
  • Wiring Harness

Related codes

Full explanation for A8
b1

Your boiler's computer memory chip is loose or missing, meaning the system doesn't know which model it is and has stopped working for safety.

High Engineer only £90-180

Parts commonly replaced

  • Code plug
  • Printed Circuit Board (PCB)

Related codes

Full explanation for b1
C1

Your boiler has stopped working because the internal fan, which clears exhaust gases, isn't spinning fast enough to operate safely.

High Engineer only £200-£450

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Venturi tube

Related codes

Full explanation for C1
d3

Your boiler has lost the signal from an external control, such as your room thermostat or programmer, preventing it from firing up.

High Engineer only £90-180

Parts commonly replaced

  • External wiring connection
  • External thermostat
  • Boiler control board

Related codes

Full explanation for d3
E2

Your boiler has detected a faulty internal temperature sensor, which means it cannot accurately monitor the water temperature and has shut down as a safety precaution.

High Engineer only £100-£180

Parts commonly replaced

  • CH Flow NTC Sensor
  • Connecting Wiring Harness

Related codes

Full explanation for E2
E9

Your boiler has shut down because it has detected that the water inside is Getting too hot, which is a safety feature to prevent damage.

High DIY-safe £120-350

What to check first

  1. Check if any radiator valves are closed and open them fully
  2. Ensure your system pressure is between 1 and 1.5 bar on the gauge
  3. Press the 'Reset' button for five seconds to restart the boiler

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Main Heat Exchanger (Flushing)

Related codes

Full explanation for E9
EA

Your boiler is failing to light the gas or isn't detecting that the flame has started, causing the system to shut down for safety.

High DIY-safe £100-£350

What to check first

  1. Check if other gas appliances in your home, like a hob, are working to confirm your gas supply is active.
  2. If it is freezing outside, check that your external condensate pipe hasn't frozen and blocked.
  3. Press and hold the reset button for five seconds to see if the boiler restarts.

Parts commonly replaced

  • Ignition Electrode
  • Flame Sensor (Ionisation Probe)
  • Gas Valve
  • PCB

Related codes

Full explanation for EA
F0

Your boiler's internal computer has encountered a critical electronic software or hardware error that is preventing it from running safely.

High Engineer only £250-£550

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

Full explanation for F0
F7

Your boiler thinks it can see a flame inside the system even though it should be turned off, which is a safety conflict that prevents it from starting up.

High Engineer only £120-300

Parts commonly replaced

  • Flame sensing electrode
  • Ionisation lead
  • Control board (PCB)

Related codes

Full explanation for F7
FA

Your boiler is still detecting a flame even though it has tried to shut off the gas, which is a safety conflict causing the system to lock out.

Emergency Engineer only £120-£350

Parts commonly replaced

  • Gas Valve
  • Ionisation Lead
  • Control Board (PCB)

Related codes

Full explanation for FA
FC

Your boiler's main control board is having trouble communicating with the display panel, meaning the system cannot correctly send or receive instructions.

High Engineer only £180-350

Parts commonly replaced

  • Main PCB
  • Display Interface Board
  • Wiring Harness

Related codes

Full explanation for FC
Fd

Your boiler has been put into a temporary reset mode because the button was held down too long or pressed accidentally.

Low DIY-safe

What to check first

  1. Press the reset button firmly once and release it immediately
  2. Wait up to 30 seconds for the display to return to a normal temperature reading
  3. If the code persists, switch the boiler's power off and back on at the fused spur switch

Related codes

Full explanation for Fd