I have already researched the archives and have found nothing. I know CEL 67 means catalyst system, but what does it mean?? I have a Comptech header and cat, with a GReddy Evo B-pipe with the stock ITR muffler (evo was too loud). Did the car just fart to cause it to go off. Any help would be much appreciated.

Ian

 

What does it mean? Well, it means your ECU ran the Catalyst Monitor and found that it failed. How did it do this? Well, it was looking at your O2 outputs. The first O2 is used to adjust injector PW, so it should constantly be swinging between .1 - .9V. The second O2, however, does NOT swing like this. It should remain at about .7 - .8V, which indicates a rich condition, or rather, a lack of air.

In theory, the Catalytic Converter USES oxygen to do its job. Since its consuming air, the output should 'look' rich. This tells the ECU that the converter is working fine. In addition, about the only time that the rear O2 should indicate lean, is on a decel condition...as the ECU cuts fuel here. Also, if you had a infared temp gun, you could check the inlet and outlet temps of the converter...the outlet should be about 100 dgr F higher than the inlet.

If the rear O2 was swinging, like the front O2...well that makes it seem like the converter isn't doing its job....this is what typically results from installing a test pipe.