my truck has been spitting out black smoke from the exhaust for the past couple of days. i replaced the o2 sensor before the cat. i read in the shop manual that this one controls the air fuel ratio by monitoring exhaust gasses. my computer was also throwing a p 0171 error message that said system running lean bank 1. i replaced the sensor now its not throwing an error but the smoke is stil there. has this happened to anyone else, or anyone know what could be causing this?

 

recent tune up or anything, are you running a higher octane gas? It may be carbon deposits. what y/m and how many miles on your rig?

 

Remember your o2 sensor works in tune with your catlytic converter as 06 ramguy stated carbon deposits will sit in your converter just changing you 02 sensor may not actually fix your bigger issue. Also just because your throwing black smoke does not mean your engine is running rich. if your cat is bad your throwing soot. Do you have a loss in power, stuuttering as if it seems the engine is choking a little bit. If so it's your cat. Do you have after market headers/exhaust. Let us know these things and we might be able to help you more. By the way your bank 1 cat is your driver's side cat. Just to let you know.

 

its an 03 4.7 4x4 std cab 129k with federal emissions, not california, so i only have one cat, and two o2 sensors, one before and one after. the truck is bone stock in the mechanical area. i changed the o2 sensor 3 days ago ( i dont have internet at home sory 4 late reply.) and it is no longer showing the eror code, it was still smoking for a day after i changed the sensor, but when i changed the sensor, before the cat, it was covered in a thick layer of soot that i think confirmed the engine was running rich. i havent notice it since, maybe the computer had to readjust? but there seems to be no moresmoke. i noticed no change orloss in power while it was broken, i gave it a tune up (plugs, filters) after i bought it 3 months ago with 121k. thank you for the help. these trucks seem to fall apartafter 100,000 miles, but it has all been wear parts ive replaced, wheel bearings, fan clutch, o2 sensor, they all eventually need replaced though but it all went within a 3-1/2 week period.

 

if i had to take a random guess, it was carbon/soot buildup. Your truck is 100k + and you put in new plugs, etc.. I think your tune up probably dislodged everything. Also, on the falling apart, thats any truck not just dodge, the only problem is they never seem to do it over a period of time. Good Luck