Black smoke is indicating that the fuel to air balance is incorrect. This means that the fuel injectors are either adding too much fuel or that the intake valves aren't letting enough air in. This could be caused by a leaking fuel injector, a faulty fuel pressure regulator, a bad air filter or if the EGR is getting blocked.

We would check the air filter in the first instance. If this is okay and you are getting the engine warning light showing we would get a diagnostic carried out to see what fault code exists ( i.e P ----- 4 numbers) as this may then indicate where the fault lies.