I have changed the o2 sensors in my wife 98 contour (major PITA). This shouldnt be a problem on my Stratus. Much easier to get to. Just wondering if its the upstream or downstream sensor. If my thinking is right bank one on the 4 cyl should refer to the upstream sensor..

 

P0420 Catalyst System Efficiency Below Threshold means that the rear O2 sensor isn't seeing the correct reduction in hydrocarbons that it would expect from a operating converter. This code is a result of comparing the upstream O2 sensor reading with the downstream O2 sensor reading and not getting the expected results. Could be either O2 sensor or Cat. A scan tool is needed to diagnose. look at the O2 sensor readings, if they are reading and responding normal the cat becomes suspect. If you wanna throw parts at it, replace both O2 sensors first, $150 for the sensors is cheaper than a $1000+ cat.

You should get a o2 sensor code if it was one of them though.

 

and there you have it...i will ask if there are regular issues tomorrow...

 

Yeah. Try and sell some parts too while you're at it.

 

i dont make commission...i couldnt care less if we dont sell a single part...the only reason they keep me on is that vie provlen to be dependable...and good in the accounting department...

 

I have an update. I pulled the code again when I got off work. I must have had a brain fart when I was typing this thread last night because the code I have is p0442 not p0420..... Well there you have 16 hour days and very little sleep will make you confuse the numbers.. Code p0442 has to do with the fuel evap system. I just bought the car and noticed that the gas cap is not original and the original is in the trunk. I am going to buy a new one and see if that solves the problem. If not I will will start trouble shooting farther.

 

P0442 Evaporative Emission Control System Leak Detected (small leak)

That would be a good place to start. OEM fuel caps are designed to seal system the way it was meant to be. Make sure you get an OEM cap, not a generic one.

There ya have it, I think you just set a 420 code yourself.
kev0420...excessive smoke causing short term memory loss and number dyslexia.[sm=pimp.gif]

 

minor evap is almost ALWAYS the gas cap..
gross evap is almost always the LDP..

 

What's the LDP master tech?

 

Good question!!!!!