What does the fault code E302 for NCB500 or NCB700 mean?

E302 means that the system pressure is too low and you may see that the system pressure gauge or on the front display indicates that the pressure in the system is below the 1 bar pressure.

To re-pressurise the system, you will find a NaviFill Link (a plastic and brass link with a green plastic leaver) on the underside of the boiler.

The green leaver needs to be pulled down slowly. The water will start to refill the system (water should be heard filling the system). You should see the pressure gauge or the pressure reading on the display rise back up between 1 bar and 1.2 bar pressure and then stop filling.

Once the pressure gauge or pressure reading on the display is between 1 bar and 1.2 bar release the green leaver and the water will stop filling the system. The error code E302 will stop and the boiler will now operate. If the error code E302 is still active, fill up the system a little more but not over 1.5 bar.

(If you do fill the system too much and the pressure gauge is too high, just bleed water from a radiator until the pressure on the gauge goes down to below 1.2 bar).