Jump to content
CaddyInfo Cadillac Forum

P-0420 Catalyst effieciency code


Recommended Posts

I have this P-0420 Catalyst effieciency code that is driving me crazy. i purchased an Eastern Converter and put it in and still the code comes up. i have been told that O2 sensors would give their own error code and i don't know what else to check. Any suggestions? It is a 2003 STS w/ 89K miles

Dan

Link to comment
Share on other sites


I have this P-0420 Catalyst effieciency code that is driving me crazy. i purchased an Eastern Converter and put it in and still the code comes up. i have been told that O2 sensors would give their own error code and i don't know what else to check. Any suggestions? It is a 2003 STS w/ 89K miles

Check with your dealer about warranty.

Some of the emission stuff, like 02 sensors and converters are covered for 100,000 miles.

I am not sure of the TIME LIMIT...either 6 years or 8 years... I am not sure.

Posted Image
Link to comment
Share on other sites

The HO2 sensors will throw a code if the heater is burnt out or the connector is loose or off. If either or both of the two on the catalytic converter simply aren't installed, they won't throw a code but you will get the P0420 code. If the new cat didn't have the fittings, he might simply have left the HO2 sensors off the cat but connected. Or, it might not be the right cat, or it might be installed wrong. Over the years I have found that about half the cats I have bought or had installed on warranty have been dropped while still in the box and will fail in a few months, throwing a P0420 code or worse, coming apart and dribbling ceramic dust or particles back into the mufflers.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

Link to comment
Share on other sites

The HO2 sensors will throw a code if the heater is burnt out or the connector is loose or off. If either or both of the two on the catalytic converter simply aren't installed, they won't throw a code but you will get the P0420 code. If the new cat didn't have the fittings, he might simply have left the HO2 sensors off the cat but connected. Or, it might not be the right cat, or it might be installed wrong. Over the years I have found that about half the cats I have bought or had installed on warranty have been dropped while still in the box and will fail in a few months, throwing a P0420 code or worse, coming apart and dribbling ceramic dust or particles back into the mufflers.

thanks, i am going to replace the two forward sensors, hopefully thaat will fix it. new law in Illinois will not allow you to renew plates until it passes an emissions test.

Dan

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...