Replacing the CAT is not a guarantee your Honda Civic will pass the smog check. With the excessive leakage of oil into the combustion chambers we have to expect your Honda has built up significant carbon build-up. We recommend a compression test to start. If high, you'll need to conduct a carbon cleaning. You may then retest your Honda Civic and if emissions are still high begin by diagnosing the high CO fault. you'll need to ensure your vehicle is in proper fuel control.
Visit our Failed Emissions Test webpage for more information about high HC, CO, and NOx.
