Originally Vaillant’s ecoTEC boilers were supplied with a pump made by a company named Wilo. These pumps are now considered to have a high failure rate and are especially vulnerable to leakage and splitting.
The Vaillant ecoTEC boiler pressure sensor (part no. 0020059717) has had three different updates since it was introduced back in 2005. The first sensor had very high failure rates, which Vaillant soon noticed and moved to carry out the new sensor.
The issue emerges from the sensor being covered by debris and sludge, which means that it is unable to detect a shift in pressure while the pump is on – which, in turn, causes the boiler to record a F75 error.
How to repair the fault code of the Vaillant F75 Vaillant F75 Fault CodeAs there are a few different explanations for the F75 code, the process of fixing it needs to be methodical.
First of all, it must be known if the fault lies with the pump or with the pressure sensor. This can also be done by actually listening to the boiler as it’s switched on and attempting to work.
You can reset the boiler by using the lockout button – the cross flame sign – and then use the heat call button, i.e. switch on the heater or use the hot water tap.