[killer ZETEC]

my car has a cel.
its for the exhaust (p0420??)
i replaced the upper o2 off of advice from a freind and reset ecm. cel came back on. car has 120,000 miles on it. anything else to look for?
its driving me nuts.

 

[faster_than_u]

the code means
Catalyst Efficiency Below Threshold (Bank 1)

so try the rear o2

 

[illinipo]

yeah either the REAR sensor is toast or the cat is dead.

i did end up finding my good rear sensor if you still want it.

 

[killer ZETEC]

ok i'll give that a shot.

 

[iminhell]

well being you replaced the wrong one, just swap the old sensor with the crappy sensor. maybe a cheap fix.
IIRC they interchange

 

[illinipo]

you cant swap front to back they are different connectors.

 

[russianwill]

if you gotta pass emissions there are ways around...if youre interested.

 

[Ryeno]

if you gotta pass emissions there are ways around...if youre interested.

true but if your 02 sensor is out, your gas millage will suffer. So you are better off fixing it.