High HC is the by-product of a misfire. A misfire can be caused by rich fuel, lean fuel, and/or a defective ignition system.
You'll need to make sure your Honda Civic's ignition/spark system is functioning properly first. Make sure the spark plugs are clean, the plug wires are on tight and are not cracked, and ensure the distributor cap is free of carbon build-up.
If all is well with the ignition system, you can inspect the emission system sensors (O2, ECT, MAF, so on...).
Look over the CO results on your Honda's VIR report. If CO appears too low or too high (even though it didn't fail for high CO) your Honda Civic is probably suffering a air/fuel mixture problem.
posted by SmogTips Support
