P0420 CEL 99 civic si

[green91]

your fuel pressure won't set the cat code, this code is set entirely on the length of time your converter is able to store oxygen, which compares the signals of your b1s1 and b1s2 oxygen sensors. however, running incorrect type and fuel pressures will make your EGTs out of an acceptable range and will damage your cat converter much faster than a normally functioning engine. most cats only have a 80-120k life expectancy.

[preferredduck]

your fuel pressure won't set the cat code, this code is set entirely on the length of time your converter is able to store oxygen, which compares the signals of your b1s1 and b1s2 oxygen sensors. however, running incorrect type and fuel pressures will make your EGTs out of an acceptable range and will damage your cat converter much faster than a normally functioning engine. most cats only have a 80-120k life expectancy.

damn mine is at 180k miles. but as i have read the cat does not gradually go bad it just goes. it ran lean until i found out what the mechanic did and i know that will mess up a cat, and it does it randomly where if the cat was gone it would be a constant thing correct.

[green91]

damn mine is at 180k miles. but as i have read the cat does not gradually go bad it just goes. it ran lean until i found out what the mechanic did and i know that will mess up a cat, and it does it randomly where if the cat was gone it would be a constant thing correct.

I'd say your car has a very lax monitoring strategy for the CAT then. They do gradually go bad over time. The CEL comes on when the catalytic converter's efficiency actually is less than a determined value in the computer. So they can be gradually going bad, but not set the CEL until its to a certain point.

Cat converters are usually a 2-trip logic detection code. Meaning it takes 2 complete drive cycles to run the monitor to check to see if the cat is good. Its possible yours on right on the borderline right now and at times just makes the mark and sometimes come up short. It probably won't hurt your car to drive with it like this, but it will get to a point where the CEL is constant.

[preferredduck]

I'd say your car has a very lax monitoring strategy for the CAT then. They do gradually go bad over time. The CEL comes on when the catalytic converter's efficiency actually is less than a determined value in the computer. So they can be gradually going bad, but not set the CEL until its to a certain point.

Cat converters are usually a 2-trip logic detection code. Meaning it takes 2 complete drive cycles to run the monitor to check to see if the cat is good. Its possible yours on right on the borderline right now and at times just makes the mark and sometimes come up short. It probably won't hurt your car to drive with it like this, but it will get to a point where the CEL is constant.

i don't want to risk screwing anything up. i have another O2 sensor im gonna put in but im also gonna pull the cat off and check it out. it was a constant CEL when the fuel pressure was low, but after that it went away for several months almost like the o2 code i used to throw, the sensor was good but the ecu couldn't figure out what was going on. i for some reason think im about t have to spend $$ i dont have to keep the car on the road and not eat up the premium gas i have to run.