Bosch fault code V or B8L534
Fault code V or B8L534 on a Bosch boiler (including Condens 7000F) means: No gas supply pressure. Flue gas pressure limiter is activated. Air pressure switch is activated. Air pressure switch is defective. 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 V or B8L534 on a Bosch boiler indicates: No gas supply pressure. Flue gas pressure limiter is activated. Air pressure switch is activated. Air pressure switch is defective.
Fixing fault code V or B8L534: step by step
- Check outside that the air intake and flue are clear (leaves, a nest, ice or snow).
- Check that the condensate trap under the appliance is filled and clean; a blocked condensate drain can make the boiler lock out.
- Reset the appliance once. If the code comes straight back, do not keep resetting it.
- If the code comes back, the small hose to the air pressure switch is often dirty or the switch itself is faulty. Have it checked by a qualified heating engineer.
Applies to
Bosch Condens 7000F, 100 kW L / R, 150 kW L / R, 200 kW L / R, 300 kW L / R, 75 L / R.
Fault code V or B8L534 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:
- V or B8L534 on Condens 7000FP, 350 L / R, 400 L / R, 500 L / R: Insufficient gas supply pressure. Flue gas pressure limiter is activated. Air pressure switch is activated. Air pressure switch is defective.
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.
This message does not point directly to one faulty part. These are the parts that most often fit this appliance:
- Bosch pressure gauge 2,5 bar 63mm AE D3/8"U € 8.15
- Nefit siphon gasket per 5 pcs for EcomLine and TopLine € 23.10
- Bosch sealing ring 10x13,5x1,5 CU gas valve 8718584813 € 32.62
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 V or B8L534 mean?
No gas supply pressure. Flue gas pressure limiter is activated. Air pressure switch is activated. Air pressure switch is defective.
How do I fix fault code V or B8L534 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 V or B8L534?
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 V or B8L534 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 →