Citroen Xsara Picasso stop - engine temperature warning

Hi, I have a Xsara Picasso (1.6 with 70kW) which shows "Stop - Engine Temperature) immediately after turning on the ignition. The coolant temperature scale is up to max. The engine is cold, the error happens any time even without the engine running. Fan is running full speed all the time when engine is on and half speed for a few minutes after turning ignition off. My car has automatic A/C (although it doesn't work any more). I received error codes P0118 and P0115 from ECU. I have already replaced the two coolant sensors (green with 3 pins/2 cables and blue with 2 pins/1 cable).