Cchristie

I have finally starting having some issues with my 03 impala. I have noticed over the past several months that I haven't had as much power when doing a hard acceleration. This past week the power has diminished dramatically, and yesterday the check engine light came on while accelerating up a hill. It seems to be ok when gently accelerating or driving within the city at lower speeds.

I haven't had a chance to read the code for the check engine light....I will do that when I get home. I did have the check engine light flash a few months back while idling and it was a code p0300 that is a general misfire.

It also on occasion has a very loud ticking noise and idles rough until the engine gets to temperature.

I am thinking either catalytic converter or downstream o2 sensor...it there any way to easily verify which it might be?

Thanks for your help

tech2

the rear 02 sensor is used only for verifying the operation of the cat (redox reactions that are occuring in the catalytic convertor). It does nothing for fuel metering control and cannot confirm a clogged convertor.

typically, a clogged convertor will cause lack of power and will set misfire dtc. The engine may bogg during a snap throttle.

You can verify a clogged cat by removing the precat 02 sensor from the problem cylinder bank then test driving. The bad cat may rattle when hammer fisted.

performing a exhuast back pressure test is a second method to test for clogged cats.