P0420 CAT low efficiency bank 1. Help!
Thread Starter
Registered User
Joined: Jan 2008
Posts: 25
From: Berkley MI
P0420 CAT low efficiency bank 1. Help!
i have a 96 T/A M6 LT1 and i have this horrible code present. the torque has seemed to drop slightly the last few thousand miles and the gas mileage isnt the best anymore. my fear is this cat might be plugged or on the way. i am looking a solution to this other thank spending $$$$ on a new cat. what down sides to buying aftermarket headers and running straight pipe? what to do with the o2 Sensors? i am not quite sure where my options lie and i could really use some ideas 
. Any help is appreciated guys thanks! < side note i dunno if this is relevant but codes NOT req mil are p0410 secondary air injection ayatem and p1416 secondary air injection ayatem bank 2.>
. Any help is appreciated guys thanks! < side note i dunno if this is relevant but codes NOT req mil are p0410 secondary air injection ayatem and p1416 secondary air injection ayatem bank 2.>
Administrator
Joined: Nov 1998
Posts: 71,097
From: Hell was full so they sent me to NJ
First, verify that it is the cat causing the code, and not the O2 sensor. Swap the after-cat O2 sensors side-to-side. If the problem stays on Bank 1, is a cat problem or possibly a wiring problem, not the O2 sensor. If the problem follows the sensor (P0430), its a faulty sensor.
If it is actually the cat, and you don't want to replace it, all you need to do is hollow it out, and put a pipe through the shell. Do both cats, not just the one side. That will work with either the stock manifolds or with headers. Or buy headers without provisions for cats.
You leave the pre-cat O2 sensors alone - the PCM needs those to manage the A/F ratio. You delete the after-cat sensors, and either get a pair of "O2 sims" and install them to make the PCM think the sensors and the car are still there. Or, have the P0420 and P0430 codes "programmed out" of the PCM, so they don't show up, or turn on the SES light. Just make sure the programmer knows how to delete the codes while avoiding a "system not ready" flag, if you have to take the car for an eimissions check where they plug into the ALDL connector.
For P0410, it may be related to your loss of performance. Check the hoses for the AIR pump, particularly the ones that connect to the AIR "check valves". If the check valves fail open, the hoses can melt, and you have a huge exhaust leak before the O2 sensors. That would cause the engine to run extremely rich on that bank. Pour too much fuel into the cat, and it may be overheating, and showing reduced activity, or even melting the cat, causing it to reduce flow.
If it is actually the cat, and you don't want to replace it, all you need to do is hollow it out, and put a pipe through the shell. Do both cats, not just the one side. That will work with either the stock manifolds or with headers. Or buy headers without provisions for cats.
You leave the pre-cat O2 sensors alone - the PCM needs those to manage the A/F ratio. You delete the after-cat sensors, and either get a pair of "O2 sims" and install them to make the PCM think the sensors and the car are still there. Or, have the P0420 and P0430 codes "programmed out" of the PCM, so they don't show up, or turn on the SES light. Just make sure the programmer knows how to delete the codes while avoiding a "system not ready" flag, if you have to take the car for an eimissions check where they plug into the ALDL connector.
For P0410, it may be related to your loss of performance. Check the hoses for the AIR pump, particularly the ones that connect to the AIR "check valves". If the check valves fail open, the hoses can melt, and you have a huge exhaust leak before the O2 sensors. That would cause the engine to run extremely rich on that bank. Pour too much fuel into the cat, and it may be overheating, and showing reduced activity, or even melting the cat, causing it to reduce flow.
Thread
Thread Starter
Forum
Replies
Last Post
PFYC
Supporting Vendor Group Purchases and Sales
0
May 21, 2015 01:04 PM