Vaillant F52 and F53 Fault Code
The F.52 and F.53 fault codes indicates a fault with the mass flow sensor, that is located just behind the gas valve connecting to the fan on Vaillant Ecotec boilers. There may be several causes of this fault, either mechanical or electrical. The meaning of F.52 is that there is a connection fault of the sensor. The meaning of F.53 is that the flow sensor function is faulty, or the filter cap is wet, filter cap is blocked or gas flow pressure too low.
As show in Image 1, you can see the mass flow sensor as shown by item 1 on the diagram. Item 2 is the connecting tube. Item 3 is the nut connecting to the gas valve. Shown in image 2 is the actual replacement vaillant part.
F52 and F53 Fault Code Repair and Solutions
In order to repair this fault, you may need to check first the sensor is connected correctly. Simply remove it and plug it back in. This will most likely address and F52 fault code. In order to fix and F53 fault code you may have to electrically test the functioning of the sensor and it’s output values, using readings available from Vaillant technical. An engineer can check it electrically, and if necessary replace this part. If the part is functioning properly, there may be a possibility that either the gas supply is too low or the PCB is at fault. Gas supply pressure can be checked by a gas heating engineer using gas testing equipment. Gas appliance repairs should be carried out by Gas Safe Register listed professionals.
Where to buy the involved parts