Using engine coolant

using engine coolant
When you say "using," you mean the engine is burning coolant? Or leaking coolant?

Check your engine oil,is it milky or seems to be too much oil in the block.You could have a blown head gasket witch allows antifreeze to seep between the gasket and enter the engine oil.

This could be injector o-rings or the EGR cooler. The cooler is easier to check and fix, any radiator shop can do this for a reasonable cost.