what is wrong with my car? catalyst efficiency below threshold?

[Jenn]

I have a 1998 Pontiac Sunfire GT and today my check engine light came on. I used my code reader and it said the problem is "catalyst efficiency below threshold" what does this mean?

I actually just got my car back yesterday from the shop, my clutch went so I bought a new clutch kit which came with a brand new slave cylinder as well. the mechanic put the new clutch and slave cylinder and also machined the flywheel. when he put it back together, he said there was a leak and said that the brand new slave cylinder was defective. so i told him to put the old one back in and he did and said it was fine. but when he went to test it apparently the transmission was also broken and he got us a new one for a good price, put it in and that fixed the car [after 6 day of being in the shop]. when we picked the car up he told us there could be a problem with the hydraulics. [when you gear in neutral, it makes a rough clutching noise] my boyfriend thinks it could be because of the old cylinder not connecting good with the new clutch. so i don't know if the check engine light has anything to do with this or if it is something new.

if anyone knows, that would be great for some help! thanks!

 

[Mad Jack]

This is something new. There are 2 oxygen sensors. One in front and one behind the catalytic converter. An oxygen sensor is basically a pyrometer measuring the exhaust gas temperature. The readings between the 2 sensors is telling you that there is a problem with the catalytic converter.

However it may not actually be a problem with the catylytic converter. With all of the maintenance that has been done there may be a wiring problem to one of the oxygen sensors.

From what you describe, the very next thing I would replace is your mechanic. Either he is incompetant or is ripping you off. Either way you are paying too much money and the car is not getting fixed right the first time.