I'm new here and don't have much knowledge in the automotive side of life so I'll apologize for my ignorance now. Any Help you can give would be greatly appreciated.

So here's the deal. Lately my '07 Fit w/ 150k miles hasn't been running as it should. The car starts fine. I always let it warm up, always do sched oil changes, go to the same gas stations aside from occassionally straying from the norm . The issue starts when I'm driving anywhere between 40 and 60mph (mostly), it happens here and there at other speeds as well, but in that range most of the time. Anyway, foot on the gas, cruising at say 50mph. take my foot off because of traffic, etc. Then slowly start to press the gas peddle again and the car starts to sputter. if I press down hard on the gas it seems fine(no sputtering) but there is loss of power(can't take off as quick as I use to). Also if I have the stereo on, set to aux, with mp3 plugged in but not playing, when the car sputters I get a crackle over the speakers in rhythm with the sputter(strange I know) electrical problem?? The check engine light just came on a couple weeks ago. Got it tested and it came back with a P0420. Did some research on that, possible CAT, O2 sensor, Exhaust. Was just looking for some educated possibilities on my specific problem. I always seem to get hosed at the garage and would like to go in there with a little knowledge. Thanks in advance for any suggestions you may have.

 

probably the 02 sensor. take it in.

 

I'd like to know how the sensor causes the crackling in the speakers.

 

Might be a coil pack. Sounnds more like it than a O2 sensor.

 

It could be while the O2 sensor is malfunctioning it throwing out electrical interference that is being picked up by the radio? In any case I'd check the connector and wiring to the sensor, if all that looks good I'd replace the sensor. Good luck