Ferroli fault code A42
Fault code A42 on a Ferroli boiler (including MegaDens 5SHR 131) means: Temperature difference too large between the 2 sensing elements of the central heating flow sensor. Reset the appliance once. If the code comes back, a part is usually faulty, often a temperature sensor. 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 A42 on a Ferroli boiler indicates: Temperature difference too large between the 2 sensing elements of the central heating flow sensor.
Applies to
Ferroli MegaDens 5SHR 131, -.
Fault code A42 on other Ferroli series
The same code does not mean the same thing on every series. Check the rating plate to see which series you have:
- A42 on BlueSense 4, BlueSense 5, 12/22/32: Temperature difference too large in the dual flow sensor.
Matching parts
Ferroli parts are available from Instalpunt; shipping to EU countries from €17.95 (€24.95 for more distant countries), usually 3–5 working days.
Based on the cause, these original Ferroli parts fit (always check the type number of your appliance):
- Ferroli cold water O-ring flow sensor Megadens 10 pcs € 17.65
- Ferroli NTC sensor (clip-on) 18 mm € 45.74
- Ferroli NTC sensor clip-on 4 connections € 48.35
Further reading on this cause
Other Ferroli codes with the same cause
- 8. — Flow domestic hot water sensor faulty
- A 07 — Sensor channel input faulty
- A 17 — Central heating sensor read error
- A 26 — Flue gas sensor measures a temperature above 90 C, or flue gas sensor 1000 Ohm resistor…
- A3 — Flue gas temperature too high Detected 3 times within 24 hours. This sensor is fitted as…
- E 02 — Central heating control sensor not connected
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 Ferroli boiler fault code A42 mean?
Temperature difference too large between the 2 sensing elements of the central heating flow sensor.
How do I fix fault code A42 on a Ferroli 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 Ferroli fault code A42?
That depends on the exact cause. In the Ferroli parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code A42 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 Ferroli boiler faults and codes at a glance →