I need help getting this code P0420! Just install 3 inches tbe with O2 bung 2 week ago but yesterday MIL light came on! I got the code erase but when I was scanning the OBD II the code was in the pending mode! Is that Normal and I'm running a test pipe?

 

yea that happens when u run a test pipe and u dont have an o2 sensor fix. if u wanna permanently get rid of it, you need that o2 sensor fix for the 2nd o2 sensor (the 2nd one at the end of the test pipe). what it does is move the o2 sensor away from the exhaust stream more hence tricking the computer into thinking that the cat is working efficiently. cats have 2 o2 sensors, one at the beginning and one at the end. the engine determines the efficiency of ur emissions by measuring the output from both sensors. for example a working cat would have a lower emissions reading on the second o2 sensor since the cat reduces emissions. with a test pipe the readings will be the same for both sensors, thus throwing a p0420 code.

just get that o2 sensor fix...search around the forums im sure you'll find it

 

Shop around and get a cel fix. This should take care of your P0420.

 

Here is a link on how to take care of the rear O2 Sensor;

https://www.evolutionm.net/forums/ev...ouler-how.html

Was your last car a VW

 

thanx looking for the fix now