Ok the tech at the dealership dropped my tranny two weeks ago to fix a squeaky clutch issue. The clutch was fine but the next day while cruising on the highway I got a check engine light come on and the car seemed to be pretty rough at high rpms. I had a guy diagnose my code as 0420. He cleared the code and I topped off with 94 octane(thinking that maybe the dealer put in some crappy gas). The next saturday while driving on the highwy again the check engine light came on again and i could hear some very loud sucking and whistling noises. Even when the car was at idle I could hear a high pitched whistle. I reset my ecu by disconnecting neg. terminal on the battery and took it for a drive. The car seemed to drive ok but the whistling sound still persists. The tech are dumbfounded (as usual) my car is completely stock and only has 7700km on her. They have ruled out anything wrong with the turbo. My belief is that when they dropped my tranny they did not reassemble the exhaust properly or reused a gasket and now i'm getting a leak somwhere. Will a leak in the exhasut cause my cel 0420??????

 

0420 is catalyst ineffecieny. it could be a leaky exaust. check it from the exaust manifold to the muffler. make sure all the blots are tight, and check around the gaskets to see if there is any visual evidence of leaks. also check to see that both o2 sensors are in tightly. good luck.

 

I had one of the sensors in the up pipe work its way out. That made a whistling noise and set off the CEL. If it is that, just screw it back in and you will be fine.

Nick