Vokera Syntesi 29 Fault codes & diagnostics

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

Combi Natural Gas 29 kW 2003-2010 Discontinued
GC Numbers 47-094-4847-094-49
Download the Vokera Syntesi 29 manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

The fault code is already on your display

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.
12 High
Versions & GC numbers

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
47-094-48 Syntesi 29 2003–2010
47-094-49 Syntesi 29 LPG 2003–2010
Just want the most common Vokera Syntesi 29 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 12 documented codes

Tap any card for details

01

Your boiler is unable to light the flame needed to heat your water and radiators, often due to a temporary interruption in the gas supply.

High DIY-safe £100-350

What to check first

  1. Check if other gas appliances, like a cooker, are working to confirm gas is reaching the property.
  2. Ensure your gas meter has credit if you use a pre-payment meter.
  3. Press the reset button on the boiler control panel and hold for a few seconds to try and restart the ignition sequence.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 01
02

Your boiler has reached an unsafe temperature because the water is not circulating correctly through the system.

High DIY-safe £150-£350

What to check first

  1. Check that the isolation valves under the boiler are in the open position
  2. Ensure all radiator valves (TRVs) are turned up to full
  3. Try resetting the boiler using the control knob to see if the pump clears the blockage

Parts commonly replaced

  • Circulation Pump
  • Limit Thermostat
  • Main Heat Exchanger (if scaled)

Related codes

Full explanation for 02
03

Your boiler has stopped working because the pipe that lets exhaust gases out is blocked or the internal sensor that checks for airflow is clogged with dirt.

High Engineer only £90-180

Parts commonly replaced

  • Fan
  • Air Pressure Switch
  • Venturi Tube
  • Flue Seals

Related codes

Full explanation for 03
04

Your boiler has detected that the water pressure is too low to operate safely, which is usually caused by a leak or air trapped in the system.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (a flexible silver hose) underneath the boiler.
  2. Slowly open the one or two taps on the hose until you hear water flowing.
  3. Watch the pressure gauge and close the taps once the needle reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop valve
  • Expansion vessel
  • Automatic air vent

Related codes

Full explanation for 04
05

Your boiler is having trouble 'talking' to your wall-mounted thermostat or remote control unit.

High Engineer only £90-180

Parts commonly replaced

  • Remote control unit (RC05)
  • Connecting wiring
  • Main PCB

Related codes

Full explanation for 05
06

Your boiler has detected a critical internal error that prevents it from operating safely, so it has shut itself down to protect your home.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness
  • Sensor assembly

Related codes

Full explanation for 06
07

Your boiler has detected a critical internal error that prevents it from starting safely, so it has shut down to protect itself.

High Engineer only £150-300

Parts commonly replaced

  • Main PCB
  • Wiring harness
  • Ignition transformer

Related codes

Full explanation for 07
08

Your boiler has shut down because a temperature sensor has detected that the burner area is getting too hot.

High Engineer only £120-250

Parts commonly replaced

  • Burner thermostat
  • Main heat exchanger
  • Temperature sensor (NTC)

Related codes

Full explanation for 08
09

Your boiler's electronic control board has developed a fault, meaning the internal computer can no longer communicate with the rest of the system.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness

Related codes

Full explanation for 09
d1

Your boiler's waste water pipe is blocked or frozen, preventing the system from draining properly and causing it to shut down for safety.

High DIY-safe £80-140

What to check first

  1. Locate the plastic pipe leading from the boiler to the outside drain.
  2. Check if the pipe is frozen and gently pour warm (not boiling) water over it to thaw.
  3. Ensure the internal trap or collection bottle is not full of debris.
  4. Reset the boiler once the blockage is cleared.

Parts commonly replaced

  • Condensate trap
  • External pipe insulation
  • Condensate soakaway

Related codes

Full explanation for d1
d2

Your boiler has detected a blockage or a fault in the system that drains away excess condensation, which has caused it to stop running for safety.

High Engineer only £90-180

Parts commonly replaced

  • Condensate sensor
  • Condensate trap
  • Electrode

Related codes

Full explanation for d2
E08

Your boiler has lost the ability to accurately measure the temperature of the water returning to it, so it has shut down to prevent potential overheating.

High Engineer only £120-200

Parts commonly replaced

  • Return thermistor sensor
  • Wiring harness

Related codes

Full explanation for E08
Status & diagnostic codes

1 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

CO Diagnostic Your boiler is currently running in a special engineer-only testing mode for checking gas emissions and is not experiencing a mechanical fault.