I have an 03' Cadillac Deville Base Sedan and it is throwing the code p0420 (Catalyst System Low Efficiency Bank 1). This code just came up today. Right now it is the only code showing. Just two weeks ago I had codes p0101 and p0410. I installed a brand new GM Mass Air Flow Sensor and a brand new GM Secondary Air Pump. And both of those codes went away. But now two weeks later, after about 400 miles the code p0420 came up. My cars power is not where it should be at. I will floor the gas pedal and the Rpms are slower to get up and accelertion is sluggish. It will increase speed decently fast but I don't think as fast as it could. I can reach speed to over 100mph. And its been doing this since I got it about a year ago. So I dont know if the CAT is completely clogged but maybe a little im guessing. And when I floor it, itll give these couple little hesitations around 35mph and then itll take off faster than it usually does after that. So I am just wondering if I need a whole new CAT or a new O2 sensor. And If I do need a new CAT, would it be bad if I got an aftermarket one or should I get the GM one. I know GM CAT is way more expensive but if you strongly suggest to get a GM one I will do that. So just wondering if I need a new CAT or maybe an 02 sensor or even something else.
have the same problem?
Monday, April 27th, 2015 AT 10:47 AM