johnrehder Posted June 26, 2012 Report Share Posted June 26, 2012 Plugged in the SCT3 tuner to read a code and its telling me: So many things to check! Anyone ever thrown this code yet??? The explanation below baffles me too. P0420 - Catalyst System Efficiency Below Threshold (Bank 1) top Indicates Bank 1 catalyst system efficiency is below the acceptable threshold Use of leaded fuel Damaged HO2S Malfunctioning ECT High fuel pressure Damaged exhaust manifold Damaged catalytic converter Oil contamination Cylinder misfiring Downstream HO2S wires improperly connected Damaged exhaust system pipe Damaged muffler/tailpipe assembly Retarded spark timing Compare HO2S upstream and downstream switch rate and amplitude. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the downstream HO2S very slow and reduces the amplitude of those switches as compared to the upstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal begins to switch more rapidly with increase amplitude, approaching the switching rate and amplitude of the upstream HO2S. Once beyond an acceptable limit the DTC is set. Link to comment Share on other sites More sharing options...
ARMORINE Posted June 27, 2012 Report Share Posted June 27, 2012 sounds like a clogged cat. though i could just be reading that wrong. you run any kind of octane booster? Link to comment Share on other sites More sharing options...
07SGT4578 Posted June 27, 2012 Report Share Posted June 27, 2012 yep clogged cat. Link to comment Share on other sites More sharing options...
2007_Shelby_GT Posted June 27, 2012 Report Share Posted June 27, 2012 How many miles? I doubt it's a clogged Cat - more likely a bad sensor, upstream or downstream of the Cat. HOWEVER, if you've been running octane booster or other additives, it could be the Cat. Go the cheap route and replace the sensors first! I can't remember, but I believe bank 1 is the drivers side. There should be two sensors per exhaust bank, one upstream of the cat and one downstream. Sam Link to comment Share on other sites More sharing options...
johnrehder Posted June 27, 2012 Author Report Share Posted June 27, 2012 Don't use octane booster, just run 93 octane daily sounds like a clogged cat. though i could just be reading that wrong. you run any kind of octane booster? Link to comment Share on other sites More sharing options...
johnrehder Posted June 27, 2012 Author Report Share Posted June 27, 2012 Where is a good place to buy the sensors? Guess i'll Google it. thanks for the tips, I'm more inclined to replace them first, I have 32k miles on it now. How many miles? I doubt it's a clogged Cat - more likely a bad sensor, upstream or downstream of the Cat. HOWEVER, if you've been running octane booster or other additives, it could be the Cat. Go the cheap route and replace the sensors first! I can't remember, but I believe bank 1 is the drivers side. There should be two sensors per exhaust bank, one upstream of the cat and one downstream. Sam Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.