ATAG fault code B4
Fault code B4 on an ATAG boiler (including Perfect-series) means: Maximum flow water temperature exceeded No flow or too much resistance in the system?. 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 B4 on an ATAG boiler indicates: Maximum flow water temperature exceeded No flow or too much resistance in the system?.
Applies to
ATAG Perfect-series, PF-SHR 15, PF-SHR 24T NZ, PF-SHR 24T(i), PF-SHR 35T NZ.
Fault code B4 on other ATAG series
The same code does not mean the same thing on every series. Check the rating plate to see which series you have:
- B4 on Perfect II, PFSHR 24 / FGO … autom: MCBA1419, PFSHR 24 T(i)(Intelligence) / FGO … autom: MCBA5417, PFSHR 24/32 Ti Intelligence / FGO … autom: MCBA5417, PFSHR 35 / FGO … autom: MCBA1419, PFSHR 35 T(i) / FGO … autom: MCBA1419: Maximum flow water temperature exceeded.
Matching parts
ATAG parts are available from Instalpunt; shipping to EU countries from €12.95 (€16.95 for more distant countries), usually 3–5 working days.
Parts per Atag-series: A Series · i Series (iCon) · Q Series · E Series · P-series (iCon) · Blauwe Engel · XL-series.
This message does not point directly to one faulty part. These are the parts that most often fit this appliance:
- Atag pump gasket 3/4" DN20 R38x25x2 mm 2 pcs € 18.95
- Atag seal gas valve 3/4" € 18.95
- Atag sealing cap exhaust pipe Ø13mm for flue gas measurement € 20.91
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 ATAG boiler fault code B4 mean?
Maximum flow water temperature exceeded No flow or too much resistance in the system?.
How do I fix fault code B4 on an ATAG 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 ATAG fault code B4?
That depends on the exact cause. In the ATAG parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code B4 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 ATAG boiler faults and codes at a glance →