Illinois Emissions
IL is OBD II testing. I passed when my car had LTs and duals with a 231/237 cam. As long as you aren't throwing a code, it will pass.
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Most of IL does not have testing. Only counties surrounding Chicago and the IL side of the St. Louis area do testing. The rest of IL is test free.
As said above, for the 10 or so counties that do have testing, it's OBD scan and gas cap test only for '96+ cars. Easy to pass.
IL does not do a sniffer test, they just check to see if your throwing a code.
you can also buy O2 sims for about $80 which will prevent your ses light from going off... that is you setup for cat removal.
if you keep your cats or buy high flow ones dont worry about the ses code.






