I just changed the coil pack and MAF sensor on my 2003 Jetta (230k miles) and literally the day after I"m getting a P0420 error code, for the catalytic converter. It was misfiring when starting in damp conditions and rough idling, but I didn't let it go on for long and it only misfired a handful of times.
What's strange to me is that it didn't throw a code until I fixed the issue...does anyone know if this is merely coincidence or if fixing it could have tripped up the o2 sensor? (or something else I can't think of)
That said, I don't notice any symptoms that the cat is acting up. I deleted the code but it came back after a few days unfortunately.
If I removed the source of the misfires, will the cat continue to decline or will it just stay mildly impaired/clogged?
What's strange to me is that it didn't throw a code until I fixed the issue...does anyone know if this is merely coincidence or if fixing it could have tripped up the o2 sensor? (or something else I can't think of)
That said, I don't notice any symptoms that the cat is acting up. I deleted the code but it came back after a few days unfortunately.
If I removed the source of the misfires, will the cat continue to decline or will it just stay mildly impaired/clogged?