A.O. Smith fault code XB2-XXXX
Fault code XB2-XXXX on an A.O. Smith water heater (including Twister) means: (Lockout) Ignition fault - Three failed ignition attempts: No gas. 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 XB2-XXXX on an A.O. Smith water heater indicates: (Lockout) Ignition fault - Three failed ignition attempts: No gas.
Fixing fault code XB2-XXXX: step by step
- Check that the gas valve at the appliance is open and that other gas appliances, such as the hob, are getting gas.
- Check that the condensate trap under the appliance is filled and clean; a blocked condensate drain can make the boiler lock out.
- Check outside that the air intake and flue are clear (leaves, a nest, ice or snow).
- Reset the appliance once. If the code comes straight back, do not keep resetting it.
- If the fault keeps returning, the ignition or ionisation electrode is usually worn or dirty. It sits in the sealed combustion section: have it replaced by a qualified heating engineer.
Applies to
A.O. Smith Twister, TWI 35-200.
Fault code XB2-XXXX on other A.O. Smith series
The same code does not mean the same thing on every series. Check the rating plate to see which series you have:
- XB2-XXXX on Twister, TWI 35-200, TWI 45-200: (Lockout) Ignition fault - Three failed ignition attempts: Air in the gas pipes.
- XB2-XXXX on Twister, TWI 35-200, TWI 45-200: (Lockout) Ignition fault - Three failed ignition attempts: Fault in the spark igniter circuit.
- XB2-XXXX on Twister, TWI 35-200, TWI 45-200: (Lockout) Ignition fault - Three failed ignition attempts: Fault in ionisation circuit.
- XB2-XXXX on Twister, TWI 35-200, TWI 45-200: (Lockout) Ignition fault - Three failed ignition attempts: Supply voltage too low.
- XB2-XXXX on Twister, TWI 35-200, TWI 45-200: (Lockout) Ignition fault - Three failed ignition attempts: The bent ionisation probe is touching a metal surface.
- XB2-XXXX on Twister, TWI 35-200, TWI 45-200: (Lockout) Ignition fault - Three failed ignition attempts: The ceramic part of the ionisation probe is broken or cracked.
- XB2-XXXX on Twister, TWI 45-200: (Lockout fault) Ignition fault Three failed ignition attempts: No gas.
Matching parts
A.O. Smith parts are available from Instalpunt; shipping to EU countries from €12.95 (€16.95 for more distant countries), usually 3–5 working days.
For fault code XB2-XXXX, the part involved is usually in the category: electrode.
This message does not point directly to one faulty part. These are the parts that most often fit this appliance:
- A.O. Smith air pressure switch Twister 45-190 € 48.93
- A.O. Smith fuse 5x20 2AT 250V € 16.31
- A.O. Smith 3-way fused terminal block € 27.18
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 A.O. Smith water heater fault code XB2-XXXX mean?
(Lockout) Ignition fault - Three failed ignition attempts: No gas.
How do I fix fault code XB2-XXXX on an A.O. Smith water heater?
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 A.O. Smith fault code XB2-XXXX?
That depends on the exact cause. In the A.O. Smith parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code XB2-XXXX 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 A.O. Smith water heater faults and codes at a glance →