Code p0442 is recorded in the your cars computer when it sees a small to medium sized leak in the system. Since your evaporative emissions system (You can read more about this at the page for code p0440) is composed of long hoses there are many places that it can leak.
The first thing you will want to do is tighten or replace your fuel cap. This is the most common cause of this code. If that does not fix it then you should open your hood and inspect all hoses for damage. If you do not find the problem with these methods then it would be best to take your car to a shop that has a "smoke machine". This machine introduces smoke into the system and then it will come out of the same place that the system is leaking. This is BY FAR the best way to fix this problem.
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