Bosch fault code A7
Fault code A7 on a Bosch boiler (including VRC) means: Hot water sensor has an open circuit or short circuit. 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 A7 on a Bosch boiler indicates: Hot water sensor has an open circuit or short circuit.
Fixing fault code A7: step by step
- Reset the appliance once; a one-off measuring error will then clear.
- Where you can reach it without opening the sealed combustion section, check that the sensor plug is seated firmly and the wiring is undamaged.
- If the code comes back, the sensor or its wiring is usually faulty (short or open circuit). Sensors in the sealed combustion section should be replaced by a qualified heating engineer.
Applies to
Bosch VRC, 24 Open, 25, 29.
Fault code A7 on other Bosch series
The same code does not mean the same thing on every series. Check the rating plate to see which series you have:
- A7 on TOP, 28-3 ZSB, 30-3 ZWB, 42-3 ZB, 42-3 ZWB: DHW NTC defective (only for ZWB ...).
- A7 on ZSN, ZWN, 18-6 KE, 24-6 KE, 24-7 KE: DHW NTC defective (ZWN).
- A7 on ZSE, ZWE, 24-4, 24-4 MFA, 24-4 MFK, 28-4 MFA: DHW NTC defective (ZWE).
- A7 on Turbo Tower, 30 HRC, 30 HRC II: Domestic hot water temperature sensor defective.
- A7 on HRC, 26, 30, 35, 42: DHW NTC defective (HRC...).
Matching parts
Bosch 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 A7, the part involved is usually in the category: sensor.
Based on the cause, these original Bosch parts fit (always check the type number of your appliance):
Bosch NTC sensor ZR/ZWR € 33.87
Bosch NTC (TTB) ZWR-5KE € 42.34
Bosch TTB sensor € 59.28
Further reading on this cause
Other Bosch codes with the same cause
- --341 — The temperature measured by the flow temperature sensor or the return temperature sensor…
- 1022 W — Storage cylinder temperature sensor defective or contact problems
- 1025 W — Return temperature sensor defective
- 1037 W — Outdoor temperature sensor defective, substitute mode heating active
- 1065 W — Water pressure sensor defective or not connected
- 1068 W — Outdoor temperature sensor or lambda sensor defective.
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 Bosch boiler fault code A7 mean?
Hot water sensor has an open circuit or short circuit.
How do I fix fault code A7 on a Bosch 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 Bosch fault code A7?
That depends on the exact cause. In the Bosch parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code A7 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 Bosch boiler faults and codes at a glance →