$re = '/(?:[\[{,:\]}]+[\[{,:\]}\s]*"(*SKIP)(*FAIL)|"(?!\s*[\[{,:\]}]))/m';
$str = '{
"Equipment Contents": [
"XL APPEARANCE GROUP",
"body-color grille",
"body-color body-side molding with chrome insert",
"luggage rack",
"15" deep-dish cast aluminum wheels",
"P235/75R15SL all-terrain OWL tires",
"power door locks",
"power windows",
"power mirrors",
"cloth captains chairs"
]
}';
$subst = "\\$0";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php