Depending on what your van failed for... This may be true. It's possible the
catalytic converter need to be "blown out" through some regular driving in
order to begin functioning properly. The fuel injectors also need to worked
in. While sitting for a long time they may have developed sticking.
Best bet in this case is go ahead and do what the smog technician recommend;
drive your van for one hundred miles and retake the smog check. If it still
fails you can begin a comprehensive diagnosis.
