urges Xtrail's head rectification?

Most likely, they are inappropriate spark plugs that I put after refinement, the most economical thing is to change them but ask them and make sure it is of adequate thermal degree according to the catalog of spark plug.

To be a rectification, the head must first be proven well ... sometimes in some vehicles when you have cargo problems, the car is pulling you in the automatic ones .. I doubt whether in all cases it is the same, but it is not necessary to check ...
luck.

Well, I already put it into the workshop, it finally had the failure at that time and because it was filtering water in the spark plugs, when the engine oil was checked, even so, the mechanic says that before rectifying head, Checara Buses, and other things with computer, before giving the final DX .. I tell you after it was, I think these forums help us a lot to understand that we are not going to our car. Pique your eyes .. hehe ami likes to understand that and why and for what they do ami truck, thank you all !!