Hello, I hope the following assists you.
P0251 and P0089 are not related to the turbo in any way. P0251 is IMV control error, P0089 is fuel pressure regulator performance fault although I haven't seen this code on the 2001 to 2007 model Mondeo only on the 2007 onwards Mondeo where it is the equivalent to P0251.
The IMV fault doesn't mean the valve is at fault, any fault in the fuel system either high or low pressure means the PCM can't control the fuel pressure correctly and the pressure is incorrect for the IMV position.
This can be due to anything from air in the fuel, a blocked fuel filter or pipe to a failing fuel pump or injector. If the fuel filter hasn't been replaced recently then it would be good practice to replace this. Check there is no air in the fuel or any leaks. After this you need to check the fuel pressure while measuring the fuel returned from the injectors, with the IMV and injector wiring disconnected the fuel pressure should reach at least 1050 bar within a couple of seconds of cranking the engine, the amount of fuel returned during this test from the injectors will help pinpoint if there is a pump or injector concern.
In around 80% of cases P0251 is caused by a fuel filter or low pressure fault rather than components in the high pressure system.
I hope this helps but if you have more questions regarding this let me know and I'll reply as soon as I'm able to.