The following page contains information relating to the Vaillant ecoTEC F.73 fault code, including what the F.73 fault code means, its potential causes, how this fault can be potentially fixed and if your boiler is worth repairing.
The F73 fault code explained
The F.73 fault code as explained in the the Vaillant ecoTEC manufacturers instructions states;
“Water pressure sensor signal out of range (too low) – Cable to water pressure sensor is broken or has a short-circuit at 0 V or water pressure sensor defective”
So your Vaillant ecoTEC boiler has a component called a pressure sensor. The pressure sensor’s job is to determine if there is enough pressure in the system for the boiler to work safely, and to determine if the pump is working sufficiently for the boiler to go onto the next part of the ignition sequence.
The F.73 fault code means that there is no communication between the pressure sensor and the printed circuit board(PCB).
So what causes F73 fault code?
The F.73 fault code can generally be attributed to one of the following issues;
(1) A faulty pressure sensor.
(2) The pressure sensor being disconnected from the wiring harness.
(3) A faulty wiring harness.
(4) Corroded connections on wiring harness, usually caused by a leaking pressure sensor.
(4) A faulty printed circuit board.
How to fix F73 fault code
Unfortunately the F.73 fault code cannot generally be fixed by an end user. If you are not qualified to work on your boiler then the only option is to reset your boiler and hope it will work until you can get it looked at by a professional.
As a general rule, once you see this fault code you will not be able to reset your boiler and it will not work anymore, although if you have an issue with the wiring harness your boiler may working intermittently.
The cost to repair the F73 fault code
The good news is that the F.73 fault generally means that your Vaillant boiler is worth repairing and you probably do not need a new boiler!
As a general guide the F.73 fault code will usually cost somewhere between £100 and £200 to repair depending on the model of your Vaillant boiler and its age and assuming you don’t have any other issues with your boiler.
In my experience this fault is usually caused by a leaking pressure sensor that has gone unnoticed and has corroded the connector on the wiring harness. Communication then breaks down between the sensor and the printed circuit board. The cost of the wiring harness varies depending on the model and age(generation) of the boiler. Sometimes corroded connectors can be cleaned up and the wiring harness can be salvaged.
Is your boiler safe to use?
Yes your boiler should be safe to use with an intermittent F.73 fault code if you have to keep resetting it, although it is extremely unlikely your boiler will reset and work at all.
My advice would be to get this fault code investigated at your earliest convenience by a suitable Gas Safe registered heating industry professional who is familiar with Vaillant boilers as it is unlikely to keep working intermittently indefinitely.
How to prevent the F73 fault code
Regular maintenance is generally the key to avoiding the F.73 fault code and other problems. This can be achieved by getting your boiler serviced annually by someone who is familiar with Vaillant boilers.
Regular boiler servicing of your Vaillant boiler allows for faulty parts such as a leaking or faulty pressure sensor to be diagnosed early and replaced as part of preventative maintenance and prevent any issues in the future.
Vaillant Repair Service South Yorkshire
I offer maintenance services for most Vaillant boilers and I cover a large part of South Yorkshire including most of Sheffield, Rotherham and Barnsley.
My services include include emergency call outs and routine boiler servicing.
I am Gas Safe registered, fully insured, carry plenty of spares for most of the Vaillant ecoTEC range of boilers and generally repair most boilers with one visit.
I provide an excellent service, I have great reviews and all parts fitted come with a 12 month guarantee for piece of mind.