Boiler Vaillant 824e turbomax ?

central heating has stopped working. it was connected with wireless thermostat, intially i thought something is worng with a wireless thermostat, so i decided to remove it and run the system with built in digital timer I have connected terminal 3 and 4. Hot water is working fine but CH does not work, it works in diganostic mode when i press "-/+" and it also work if a run a test program P1 and P2, but other then this CH does not repond and boiler is showing code S.30 (no demand of heating something like this). any clue what might be the issue ? water pressure is between 1.4 bar and 1.7 bar. on test progam and diagonistic mode heating work perfectly fine but only for 15 minutes.