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I have a 2002 9-5 Aero that has recently been plagued by a significant loss of boost. At WOT I might see about 3-4psi of boost. I had also noticed that the exhaust (Remus Sport Exhaust) seemed to have gotten slightly quieter than I remembered.
Prior to the loss of boost I had a check engine light. I went to Autozone to get the code read and message came up as code P0420 (Catalyst efficiency low-bank 1). The salesman that gave me the printout said it was probably my O2 Sensor, but he didn't think that an O2 sensor would cause a major lack of boost. He suggested that I test for vacuum leaks and to try a fuel injection cleaner prior to purchasing a new O2 sensor. I got a big bottle of Techron and I got the car tested for vacuum leaks (there were no leaks, but I'm sure the Techron did some good).
I tried to diagnose the problem further by searching for prior posts of cars that have had similar symptoms. I had tried all of the following things to no avail.
Swapped BPV with a known good unit.
Swapped MAF sensor with a known good unit.
Swapped BCV with a known good unit
Checked wastegate actuator (seemed to be moving fine)
Had the car tested for vacuum leaks (with smoke machine)
After testing all of the above to no avail I was beginning to get quite discouraged. As a last resort I disconnected the exhaust at the turbo. At near WOT I noticed an immediate difference. The boost gauge read about 12psi. This leads me to believe that my catalytic converter has indeed failed. There is definitely something clogging or causing extreme backpressure somewhere within my exhaust.
This was the perfect excuse for me to order a 3 Downpipe with racecat. However, without truly knowing why the Cat failed in the first place, I am very leary of putting on a new unit without correcting the original problem. I have read that a bad O2 sensor can cause a car to run lean or rich (which can lead to possible converter problems).
Will replacing the Converter get rid of the check engine light? Is the O2 sensor bad and the direct reason that the Cat failed? Or is it good and its reading that the Cat went bad?
Does anyone have any suggestions/comments/feedback? Any and all input would be greatly appreciated.
posted by 72.74.205...
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