Changing the thermostat

Hello, what does it mean: "the van states why the check engine light is on"? No check engine light will tell you to replace any component. Diagnostic testing is needed to figure out what is going on and why. I can't weigh in on expense to fix, you can contact some shops near you via this link to get some quotes if you wish; I'd recommend proper testing be performed. www.repairpal.com/repair-shops