We will assume that your Dodge Ram Diesel has an illuminated check engine light, and subsequently it failed the smog check. A vehicle which has an illuminated check engine light automatically fails the smog test. Your Dodge Ram 3500 might be experiencing a problem which is only transmission related, however since the check engine light is ON, it will fail the smog check. It should be noted, that most often, transmission faults do increase emissions when causing incorrect shifting patterns or idle speed faults.
posted by SmogTips Support
