[trentgreene]

You are very much legally in the clear to call yourself an engineer, even if your actual title is "Solutions Engineer" (i.e., sales).

You cannot however represent yourself as a licensed professional (engineering or otherwise) without actually having that license. That's what's illegal.

[grovesNL]

That could be the case wherever you live, but this isn't true in general. The word "engineer" is protected title in some countries (without requiring additional qualification such as the word "professional" or "licensed").

[Izkata]

I think I remember reading it's not even consistent across the US, that some states have the same protections on the title.

[Tijdreiziger]

Your username suggests you’re from the Netherlands. AFAIK ‘engineer’ is not a protected title here (as opposed to ‘ingenieur’, which is protected).