CEL and Whistling Noise

[JordanIsHere]

About 2 weeks ago my CEL came on, I pulled the code at Murray's Auto: "P0420 Catalyst System Efficiency Below Threshold (Bank 1)" Obd-codes.com said the first thing i should do is reset it and see what happens. I did so and it came back on after about another 200 miles. Since it came on the second time I've noticed it makes a whistling as the RPM's climb (I'm not sure what RPM range since I don't have a tach yet). I had the same problem on my 96 Hyundai until the trans blew it was totaled (but thats a whole other story). I never solved the problem on the Hyundai, and I asked on a Hyundai forum, but they just joked about me probably having a "Whistler Tip" installed on the car. So hopefully you scooby guys will spare me the Bubb Rubb jokes and help me out? :razz: I did some searching and found posts with similar problems, but no solutions. It's probably hard to diagnose the problem without actually hearing it, so I can record a sound clip with my laptop if necessary. It's hard to tell if it's coming from under the hood or back in the exhaust area.

Thanks!

[Huffer]

You have an exhaust leak, probably on the top of the catalytic convertor.

The PO420 code is related to the catalytic convertors not "cleaning" the exhaust flow enough, OR there is too much flow for the rear O2 sensor.

Possible causes/solutions:
Leaky exhaust/results in inefficient exhaust flow
Bad front O2 sensor resulting in overfuelling resulting in a overfuelled catalytic convertor
Bad rear O2 sensor resulting in non-existent O2 flow detection

My recommendation is to drop the exhaust down, see if you have an exhaust leak, if you do, have it fixed and drop in a couple of Bosch 3-wire O2 sensors from www.o2sensors.com (http://www.o2sensors.com)