Only cold air from my heater on e300 turbo diesel

go to the radio's manufacturer's site and click on support for manual

Plz check that heater core is not clogged. If coolant isn't circulating through heater core it may require to be backflushed.

The intake air temperature sensor on a 6.6L diesel is part of the mass air flow sensor, located just outside the air filter housing, in the intake air snorkle going to the engine. The other one is for the turbo system and is located directly at the top of the engine in the inlet pipe for the turbo. This on is the intake temperature heater / sensor, and will set a totally different code relating to the turbo. The one you want is incorporated with the MAF sensor. Usually code P0101 sets.

you sound on the right track it could have been pulling oil from the crankcase through the crankventilation valve

"Have you replaced your air filter lately?" think about the ford commercial tune on that one lol!

Yes check the heater control valve on bulk head between wipers lilttle elec unit with 2 pipes going into it, about £26 to replace,

There are no plugs on a turbo, might be only a sensor but very unlikely, there are heater plugs in the engine on each cylinder, and their work is to heat up the cylinder for correct firing of the diesel/air mixture when engine cold.

When it is cold you have to plug them in. Where do you live? Does it have a heater probe. If it is cold climate you need to plug it in at night,

check air hoses from turbo to air box if any holes it will be sucking in too mutch air and bypassing the airflow meter situated in hose this will cause the fault to occure.

yes very much so in the winter.. diesel fuel can gel if it gets cold enough ...that why you see semi trucks sitting on the sholder of the road on really cold days when there fuel gels,,,,,,if you live near a truck stop or or where trucks fuel look for HOWES fuel treatment it works great...if your car has a block heater on it keep it plugged in on cold days car will stat easier ... hope this helps...