I tried search to see if anyone else was aware of a manifold problem on the 01 and 02 Civics but came up empty handed. I just found out that the manifolds have been cracking at the welded joints where the manifold bolts to the engine. I didn't even notice it in mine but a mechanic did. Sure enough when I revved the car up a bit and held my hand at the left side of the exhaust where it bolts on I could feel the leak(BE CAREFUL NOT TO TOUCH EXTREMELY HOT). Turns out Honda(Canada anyway) has been warranting them for 130K or 8 years. Mine is not quite 5 yrs but I have 189K, since the catalytic converter is part of the manifold it is a $1000Cdn part. My guess is most people won't even notice it and will go over the kms before the problem becomes noticible. My check engine light just came on so my guess is the O2 sensor is alerting me of a problem. There is a SAFETY ISSUE here too, exhaust fumes will be pulled in through your heater intake.

If you own this car and have under 130K get in and get it replaced while it is still covered.