I have been told both of these things can help to pass smog I have also been told it makes no differs=enc I change my oil every 3000 to 5000mi and change air filter about every 30000mi it has 140,00 mi and seems to be in great running order
So will new spark plugs, a new PCV valve, a new fuel filter, cleaning the throttle body,…
Wait, … what was the question?
If this Corolla is newer than 1996 and the CEL is not on, you will pass emissions check. Does your county also do a safety check? Better check the brake pads, too.
No safety checks in CA, just smog. As mentioned if the CEL is not on and the car is not gulping gas you should be fine. The single most important thing is to remember to make sure the car is warmed up before the test, and don’t let it sit on the lot for one hour before they do the test. Happened to me, barely passed, but the numbers were not good.
Early filter changes won’t help at all. If it isn’t broken, you don’t have to fix it. If it’s in great running order, it won’t fail.
I have a OBD-I 1993 Caprice that is only driven about 4k a year. In 2007 it just passed Emissions testing in NJ. The readings were 70-80% of the max allowed values. Before it was taken in for the 2009 inspection, I drove it about 50-70 miles the day before and made sure it was fully warmed up before getting into the inspection line. This time the readings were around 20-25% of the max values. The Caprice had no work done on it between 2007 and 2009.
A few years back I bought an 81 Nissan pickup. It failed inspection on emissions, I pulled over and removed the air filter and got back in line. It passed on the second try and I bought a new filter for it.
If your car is 1996 or newer, if the CEL light is off it should pass though. A clean air filter and putting a few miles on it before inspection wouldn’t hurt though.
Make sure the car is thoroughly warmed up before you get it tested. I once failed an emission test that way, there was nothing wrong with the car!