mercury cougar black smoke problem on 2002 Mercury Cougar

My 2002 Mercury Cougar has black smoke coming out the tail pipe when idle at times and when accelerate hard service engine light is on code reads po401 replace 02 sensor down stream @ back of car it don't run rough at all.

by in Shellman, GA on March 28, 2014
1 answer 3 comments
ANSWER by , March 28, 2014
Scan test needed! Live data will help a bunch!
COMMENT by , March 28, 2014
what do you mea by scan test and push rod and camshaft, that mean I need a new engine
COMMENT by , March 28, 2014
what do you mean by scan test and push rod and camshaft, that mean I need a new engine
COMMENT by , March 28, 2014
what do you mean by scan test and push rod and camshaft, that mean I need a new engine