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Want to make your hot air heating system more energy efficient? This guide covers what homeowners need to know about boosting energy efficiency in hot air heating systems: practical tips, maintenance advice, and upgrade options to help you save money and reduce your carbon footprint. At 0800 Homefix, we specialise in optimising heating systems to ensure they deliver maximum efficiency and comfort for your home.
The Vaillant F64 error code points to a serious issue with the Main Printed Circuit Board (PCB)-also known as the boiler’s PCB-housed within the electronics box of your boiler. This core component manages all electrical operations in your boiler, so when it develops a fault, you’ll likely see heating or hot water failures. If your Vaillant boiler is showing F64, don’t ignore it-it requires prompt attention to prevent complete boiler shutdown. These types of faults are common across popular models like the vaillant ecotec plus and vaillant ecotec.
The F64 error is one of several Vaillant boiler error codes, including F 61, F 62, F 63, and F 64, which all relate to electronic or PCB faults.
At 0800 Homefix, we specialise in resolving complex electrical faults like the F64 PCB fault on Vaillant boilers with precision and care. Here’s what you need to know.
What Does the F64 Fault Code on Vaillant Mean?
The F64 on Vaillant boilers occurs when the internal diagnostics detect abnormal temperature readings or failed communication between sensors and the PCB. These abnormal readings may be outside the permitted or expected range (wrong range), and the F64 code can be triggered by a safety relevant sensor detecting this. It typically suggests:
Faulty or loose sensor connections
Faulty temperature sensors or thermistors
Faulty NTC thermistors or NTC sensors on the flow and return pipes
A defective main PCB unit
Issues with the coding resistor on the PCB can also cause communication errors leading to the F64 fault.
This error can cause your heating or hot water system to become unreliable or stop working entirely.
Signs of an F64 Fault
You might notice:
Boiler frequently locking out
Boiler restarting on its own
Error code F64 displayed on screen
No hot water or heating
Clicking or buzzing from the boiler’s control board
Boiler displays safety switch off or fails to ignite (unsuccessful ignition/ignition unsuccessful)
Flame signal errors or irregularities shown on the display
Some users may try pressing the reset button to clear the fault, but this is only a temporary fix and does not address the underlying issue.
These signs point toward an F64 PCB fault Vaillant and shouldn’t be ignored.
Causes of the Vaillant F64 Error
Several issues can lead to the F64 Vaillant boiler fault:
Water ingress or condensation damaging the PCB
Age-related wear of the control board
Electrical surge or short circuit
Loose wiring or poor sensor connections
Corrupted boiler firmware
Damaged or short circuited wiring harness or cable harness causing sensor or PCB faults
Faulty water pressure sensor, return temperature sensor, or flow temperature sensor leading to abnormal temperature sensor readings
Issues with pressure change detection or water circulation causing permanent temperature difference or implausible temperature difference between flow and return sensors
Problems with gas valve regulation, gas valve, gas group resistor, or gas supply affecting PCB operation and triggering faults
These can cause incorrect temperature readings, breakdown in safety communication, or failure to fire the boiler.
Troubleshooting Tips for F64 Error Code
Before calling an engineer, try these checks:
Reset the boiler: Sometimes clears minor faults
Check for other error codes: You may have multiple faults active
Verify stable water pressure: Low pressure can sometimes trigger sensor faults
Check for faults with the flow sensor, return temperature sensors, or NTC sensor as these can trigger the F64 error.
Only qualified engineers, such as a Gas Safe engineer or heating engineer, should carry out repairs involving the PCB, sensors, or electronics temperature checks.
⚠️ Important: Do not open the boiler casing. PCB work, safety switch, and electronics temperature checks are critical safety features and must only be carried out by a Gas Safe registered engineer or other qualified engineers.
How 0800 Homefix Can Help with Vaillant F64
At 0800 Homefix, we offer reliable repair solutions for all Vaillant error codes, especially PCB-related ones. Our services include:
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Full diagnostic test of PCB, electronics box, safety relevant sensor, and connected sensors
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Checking electrical continuity and component response
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Inspecting and replacing ignition lead, ignition cable, or defective electrode lead if ignition faults are detected.
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Checking the condensate pump and primary heat exchanger for faults that may contribute to error codes.
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Testing and replacing faulty temperature sensors or thermistors
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Replacing damaged or water-affected PCBs with genuine Vaillant parts
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Safety checks and system recalibration after repair
We ensure your heating system returns to full, safe operation.
Preventing Vaillant Boiler F64 Faults
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Book annual boiler servicing to catch early PCB wear
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Keep the boiler in a dry, well-ventilated area
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Fit a surge protector to prevent electrical spikes
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Address water leaks immediately to avoid corrosion
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Regularly monitor flue gas temperature and electronics temperature to ensure they remain within the permitted range.
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Have your engineer check the water pressure sensor, NTC sensors, and flow and return sensors during annual servicing.
Routine maintenance reduces the risk of Vaillant F64 faults and prolongs your boiler’s lifespan. If persistent faults continue despite regular maintenance, it may be time to consider a new boiler for improved reliability.
FAQs
What does the Vaillant F64 fault mean?
It means your boiler’s main PCB or connected sensors have failed. The F64 is one of several fault codes that can be triggered by issues such as safety switch-off, insufficient quantity of water, or problems with the flow sensor.
Can I fix the F64 code myself?
No, PCB work is highly technical and must be handled by a qualified engineer. Faults may be caused by issues with the coding resistor, gas group resistor, or cable harness, which require professional diagnosis.
Is F64 a major boiler fault?
Yes. It can be caused by flame simulation errors or safety switch-off, and always requires a qualified engineer. It can cause full boiler failure and safety risks if ignored.
How fast can 0800 Homefix respond?
We provide rapid diagnostics and repairs-often on the same day.