A4 B6 2001 2L petrol issues

[Grover2000]

Hi can anyone advise on the the issues with my A4?

It has been parked up for a fortnight and noticed that a coolant warning symbol has come up on the dash. Investigation shows that no water leak. Temp gauge is erratic and the car just blows out cold air. Tried to open the bleed screw but still the same.

Took the for a scan and the results are below

17947 p1539 clutch switch input circuit f36 implausible
17544 p1136 mixture adaptation system too lean
17927 p1519 A camshaft position actuator circuit bank 1 malfunction short circuit to another valve.

Any help to resolve the the coolant issues as there is no result showing on the scan

also noticed the brake pedal becoming stiff to press. Already replaced brake servo twice. Looked at the battery area and all seems dry.

Any help is greatly appreciated

grover