2 months after header install and now code P0420
Thread Starter
Race Director
Joined: Mar 2005
Posts: 10,078
Likes: 17
2 months after header install and now code P0420
I have had this code twice in the last couple of weeks. It says something like "catalyst bank 1 below efficiency threshold".
Does this mean I probably have an 02 sensor (or several) going bad? The car is a '99 with ~50k miles. Any thoughts would be appreciated.
The stock cats were replaced with the Dynatech system from headers to the mufflers.
Does this mean I probably have an 02 sensor (or several) going bad? The car is a '99 with ~50k miles. Any thoughts would be appreciated.
The stock cats were replaced with the Dynatech system from headers to the mufflers.
Drifting
Joined: Jul 2002
Posts: 1,484
Likes: 0
From: Morgan Hill Ca.
OK, here is the skinny. The system compares the rear O2 to the front one and if they are in an acceptable range every thing is hunky~dory 
. If the HO2S #2 is out side that range for an extended period of time and De PCM Sets-a-da code P0420. 
This indicates that the three-way catalytic converter oxygen storage capacity is below a threshold considered acceptable. 
or the HO2S #2 is hosed! 
Book says to check-a-d-following
Verify that the three-way catalytic converter is an origional equipment part. (ok forget that one)
Inspect the converter for damage, dents, holes etc. (doubtful but check anyway)
Insure the converter does not rattle. some times the grid inside comes loose. (I know on the higher HP cars the Random Techs would blow out)
Inspect the exhaust system for leaks. (Mmmm May be)
Insure the HO2S #1 and HO2S #2 are secure and that the pigtails and wiring are not damaged or contacting the exhaust. (Another maybe!)
Not in the book.
The HO2S #2 passed the initial start up test so the system is not flaggin it as bad, but it could be. After you make the above checks I would swap the HO2S #2 with the other bank to see of the problem goes to the other bank.
Or if you have the tools and time, swap the cats to see if the problem follows them.
Good luck.
. If the HO2S #2 is out side that range for an extended period of time and De PCM Sets-a-da code P0420. This indicates that the three-way catalytic converter oxygen storage capacity is below a threshold considered acceptable. or the HO2S #2 is hosed! Book says to check-a-d-following
Verify that the three-way catalytic converter is an origional equipment part. (ok forget that one)
Inspect the converter for damage, dents, holes etc. (doubtful but check anyway)
Insure the converter does not rattle. some times the grid inside comes loose. (I know on the higher HP cars the Random Techs would blow out)
Inspect the exhaust system for leaks. (Mmmm May be)
Insure the HO2S #1 and HO2S #2 are secure and that the pigtails and wiring are not damaged or contacting the exhaust. (Another maybe!)
Not in the book.
The HO2S #2 passed the initial start up test so the system is not flaggin it as bad, but it could be. After you make the above checks I would swap the HO2S #2 with the other bank to see of the problem goes to the other bank.
Or if you have the tools and time, swap the cats to see if the problem follows them.
Good luck.
Last edited by BlueDragon; Jun 16, 2005 at 12:43 PM.
Thread Starter
Race Director
Joined: Mar 2005
Posts: 10,078
Likes: 17
Originally Posted by BlueDragon
OK, here is the skinny. The system compares the rear O2 to the front one and if they are in an acceptable range every thing is hunky~dory . If the HO2S #2 is out side that range for an extended period of time and De PCM Sets-a-da code P0420. This indicates that the three-way catalytic converter oxygen storage capacity is below a threshold considered acceptable. or the HO2S #2 is hosed!
Book says to check-a-d-following
Verify that the three-way catalytic converter is an origional equipment part. (ok forget that one)
Inspect the converter for damage, dents, holes etc. (doubtful but check anyway)
Insure the converter does not rattle. some times the grid inside comes loose. (I know on the higher HP cars the Random Techs would blow out)
Inspect the exhaust system for leaks. (Mmmm May be)
Insure the HO2S #1 and HO2S #2 are secure and that the pigtails and wiring are not damaged or contacting the exhaust. (Another maybe!)
Not in the book.
The HO2S #2 passed the initial start up test so the system is not flaggin it as bad, but it could be. After you make the above checks I would swap the HO2S #2 with the other bank to see of the problem goes to the other bank.
Or if you have the tools and time, swap the cats to see if the problem follows them.
Good luck.
. If the HO2S #2 is out side that range for an extended period of time and De PCM Sets-a-da code P0420. This indicates that the three-way catalytic converter oxygen storage capacity is below a threshold considered acceptable. or the HO2S #2 is hosed! Book says to check-a-d-following
Verify that the three-way catalytic converter is an origional equipment part. (ok forget that one)
Inspect the converter for damage, dents, holes etc. (doubtful but check anyway)
Insure the converter does not rattle. some times the grid inside comes loose. (I know on the higher HP cars the Random Techs would blow out)
Inspect the exhaust system for leaks. (Mmmm May be)
Insure the HO2S #1 and HO2S #2 are secure and that the pigtails and wiring are not damaged or contacting the exhaust. (Another maybe!)
Not in the book.
The HO2S #2 passed the initial start up test so the system is not flaggin it as bad, but it could be. After you make the above checks I would swap the HO2S #2 with the other bank to see of the problem goes to the other bank.
Or if you have the tools and time, swap the cats to see if the problem follows them.
Good luck.
