Rep Power: 0

I've got an '03 Si HB, 170k miles, thats throwing a CEL. I bought the car almost 2 years ago as a commuter...had 150k on it then. Its got an aftermarket CAI, K&N filter, and now has a Magnaflow Cat, and Cat Back Exhaust.

I haven't had it scanned, to see what code(s) its throwing, but my main issue is the exhaust fumes/gas odor coming up in the cabin. The car runs fine, idles a little lower than I think it should, but doesn't stumble or load up. Even with my foot in it, I'm getting about 28mpg.

Any help will be greatly appreciated.

 
Rep Power: 210

normally caused by a cracked header, or leak between the header and cyl head...you have an exhaust leak somewhere in the engine compartment, so just inspect everything

 
Rep Power: 0

Got it scanned the other day.... It threw the knock sensor code, and both O2 sensors. Guess I'll fork out some coin for the sensors, and see where that gets me.

BTW, I had it on the rack this weekend changing oil and such, and couldn't find any cracks in the header or leaks at the block. Does anybody think it could be drawing exhaust fumes in from the hatch, at the back where the magnaflow tips don't quite come out and clear the bumper cover? Just a thought... I know it's grasping at straws, but I'm at wits end.......

 
Rep Power: 188

What does it smell like? Could it be coolant/oil smell, or is more like a gas smell..

the leak could be anywhere, also malfunctioning parts like , cat, muffler ETC... can also cause this issue,

in regards to your question about it coming in the back, if your hatch seal is going bad, (weather stripping) it could be passing into the car that way also.