AWB fault code E 91
Fault code E 91 on an AWB boiler (including ThermoSystem) means: Detection of the expansion board of the central boiler control. Reset the appliance once. If the code comes back, a part is usually faulty. You can check the water pressure and settings yourself; leave work on gas-carrying parts to a certified gas engineer.
After a safety alert (gas, flue gas, combustion), reset no more than once and call in a certified gas engineer. If you smell gas, call your national gas emergency number or 112 immediately.
Cause
Fault code E 91 on an AWB boiler indicates: Detection of the expansion board of the central boiler control.
Fixing fault code E 91: step by step
- Switch the appliance off at the mains for 30 seconds (unplug it), then switch it back on.
- Is it about communication with the thermostat? Then check the thermostat connection and wiring.
- Reset the appliance once. If the code comes straight back, do not keep resetting it.
- If the code comes back, the PCB or burner control unit is probably faulty. Have the appliance read out first to be sure.
Applies to
AWB ThermoSystem, HR 120, HRM 80/2.
Matching parts
AWB parts are available from Instalpunt; shipping to EU countries from €12.95 (€16.95 for more distant countries), usually 3–5 working days.
This message does not point directly to one faulty part. These are the parts that most often fit this appliance:
- AWB gasket mounting valve 5 pcs € 25.82
- AWB ionisation pin set € 57.08
- AWB ignition pin (set) € 65.24
Fix it yourself or call an engineer?
Always consult the manual for your appliance and work safely. If in doubt or if the fault comes back, call in a qualified professional. A question about a part? Write to us at info@instalpunt.nl.
Frequently asked questions
What does AWB boiler fault code E 91 mean?
Detection of the expansion board of the central boiler control.
How do I fix fault code E 91 on an AWB boiler?
First check the cause described above. Then restart the appliance using the reset button. If the message comes back, a part usually needs replacing or the fault needs to be repaired by a qualified professional.
Which parts do I need for AWB fault code E 91?
That depends on the exact cause. In the AWB parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code E 91 myself?
You can reset the appliance and check things like the water pressure or settings yourself. Work on gas-carrying parts must be left to a certified gas engineer.
All AWB boiler faults and codes at a glance →