code P0420,P0430 bad gas mileage

[gburg1.8]

I have a 00' GXE w/ 120k. I have had these codes since about 98k and before that two O2 sensor codes. my friend at the dealer said they have trouble with the converter breaking down. i am also only getting about 280 miles to the tank and a loss of power. instead of spending $600 on another low power converter, any ideas on converting to a header and 2.0 style exhaust?

[nametakennow]

I'm not sure what kind of catalytic converter you're buying, but $600 is outrageous. You can pick up a good aftermarket one for $50-100. I'd go that route.

The one maker of a header for the 1.8 is currently still in the process of changing hands, so there aren't any being made right now. You may be able to find one used. Using a 2.0 exhaust wouldn't do much, and would actually choke you off if you put on a header.

[gburg1.8]

the converter is two seperate converters welded together and bolts directly to the exhaust manifold, even aftermarket is $450 to $550. any suggestions?

[xru5tyx]

look for another sentra in the middle of the night and jack theirs

[Wc240]

my advice, fix the problem before you throw a cat on it. id get your o2 sensors checked. if it is a bad cat, i dont think that and your mileage are related. something had to kill the cat.

[nametakennow]

the converter is two seperate converters welded together and bolts directly to the exhaust manifold, even aftermarket is $450 to $550. any suggestions?

I'd forgotten about how weird 1.8's exhaust systems are. I don't see why a cat would cause bad mileage, though, so I have to agree on really identifying the problem first.

That said, slapping on a header and either tricking the rear two O2 sensors or installing aftermarket cat(s) and just the sensors behind it would work too, though you may still have whatever problem it is.