Hi all,
New to this group and hoping you all can help me. I just purchased a 2005 sebring that have 61k on it. Had it checked out by a local mechanic everything checked out good. This is day 3 of ownership and when I pulled up to a stop sign I saw that the RPMs dipped pretty low (about 550). When I accelerated I had no issues and no check engine light. I arrived home and put the car in park and same issue RPMs dipped to about 550 then rose to 750 then back down again. Caused a slight vibration but nothing serious. Just confused as to what this could be? I've read through a ton of forums. Some saying it could take a while for computer to learn my driving, others stating could lead to an oil light and the list goes on. Just nervous seeing as how I just purchased this car and I'm praying it's not a lemon! Drives wonderfully and again no warning lights on and no codes being thrown out. Today was the very first warm day here I'm not sure if it's just because the engine is warmer verus all the snow we've had over the week. Thanks for any advice!

 

A lot of times carbon in the IAC valve can cause a wandering idle. I've never removed one on a 2.7 but normally they are located near the throttle body. Try taking it out and soaking it in some carburetor or fuel injector cleaner. A dirty throttle body can also cause idle issues. The fact that it has so low miles leads me to believe that it was used mostly for local driving which can cause a buildup of carbon. Try and get it out on the highway at 60-65 mph for a sustained period. That should help clear out some of the carbon in it.

John

 

Thanks for the advice, I am going to try and take it out on the express for some time tonight and see if that helps at all before I dig into it. I have to top off the gas tonight, should I try a fuel injection that why to try and help? Not sure if doing it that way will help at all but figured I would ask before I put gas in her.

 

I would try high speed driving before I added anything to the fuel system. If that doesn't work then you can try one of the fuel system cleaners that they sell. I've never really used them personally so I can't vouch for their effectiveness.

John

 

Alrighty ladies and gents, I have a 2005 Chrysler sebring 2.7 two edition. I have been getting the P0420 code since it started dropping below 30 degrees at night. During the winter the light was on all the time, but when it got warm out, let's say around 40s and up it would should it else off. I have replaced one of the O2 sensors hoping it wasn't a catalytic converter, but it still remains. I am trying to figure out how to fix it without messing with the cat, and it I have to what do I need and how should I go about doing this

 

Welcome to the forum. If you can't find a thread that's directly related to your problem, it's best to start a new thread with a title that will describe your own problem. That helps people who come after to find what they are looking for. Anyway, about your problem:

The 2.7L engine has four O2 sensors. There is one upstream and one downstream of each of the two catalytic converters. Your code indicates a problem with the cat on bank 1, which is the rear bank of cylinders.

There could be several possible causes of the trouble:

P0420 CHRYSLER Catalyst System Efficiency Bank 1 | AutoCodes

It could be spark plugs, injectors or something more expensive.

For your information, O2 sensors work in pairs. The computer compares the reading from the upstream sensor to the reading from the downstream sensor and draws a conclusion as to how well the cat is working. As the sensors age, the computer makes adjustments, so if you have one brand new sensor in there you may have confused the computer. The car is now 11 years old and you should expect to have some issues as it ages.