my @file = <DATA>;

##</code><code>##

open(INFILE, "< file.log")
         or die "Cant open file : $!";

open(OUT, "> results.txt")
         or die "Cant open new file : $!";

$pattern = "Error code 2";

my @file;
while (<INFILE>) {
	print OUT @file if (/$pattern/ and @file);
	push @file, $_;           # push on the current line
	shift @file while (@file > 3); # shorten to 3 elements
}

close INFILE;
close OUT;