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Car failed the hi nox area of emissions. Ive replaced the cts and pcv since. Just wondering if I should pull codes even though i'm NOT getting any cel's. Car is driving fine otherwise and idling under 1k. Noob question but i'm a bit unfamiliar with toyota. I thought cels usually came on after something went bad.
When a vehicle fails for high NOxs its most likely the EGR, EGR modulator, or the VSV that controls the EGR modulator. The Catalytic converter also can contribute to NOX failures but should be the last option.
Do some tests on the EGR components to see if they test out fine.
You can also try a gallon or 2 of alcohol in the tank after you change the filter... high nox can ultimately mean bad cats, but i start with the easy fix first.
CO gives you one free retest for every paid test. Does GA do that?