Cel P0421

[laxmid99]

2002 p5 bone stock.

last week finally brought the car in to replace the #1 Cat and both O2 sensors. Now I am getting this code P0421 WARM UP CAT EFFICIENY BANK #1. This is a O2 sensor call out, correct? I cleared it and it came up again and I took it back to the garage, they said they would clear it and they would have to do extensive troubleshooting if it comes back a third time.

Has anyone battled this beast. If you have any advice please post.

 

[i12drivemyMP5]

Was catalytic converter in a different thread....

 

[Diehonda]

you say that the first cat was replaced and the code came back? Did they get one from a junkyard or something?

 

[Crazee D]

hey this is one of my codes
let me check my info on it...brb

 

[Crazee D]

yup
warm-up catalyst system efficiency below threshold
Could be a bad sensor or a bad cat (DOWN KITTY!)
Unless u have an exhaust leak or a detached O2 connector.
Check the harnesses. Have you had any work done on it recently?
Maybe changed octane?
my O2 sensor thread
http://www.msprotege.com/forum/showthread.php?t=94788

 

[Crazee D]

dtc 0421