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2007 5.3 “catalyst efficiency below threshold” bank 1 and 2??!!


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Hi all,

 

I have a 2007 5.3 throwing codes for Catalyst efficiency bank 1 and 2. I have been chasing this like crazy and am at whits end…hoping an expert can help.

 

In my efforts to resolve I’ve just done in the past 8 weeks…

 

New fuel sending unit (old one rotted)

8 new plugs (AC Delco 41-162)

8 new plug wires 

new driver side valve cover (updated style) and pcv hose (to ensure no leaks)

new exhaust manifolds and gaskets both sides 

2 new cats/ y pipe (Davico $550) 

4 new oxygen sensors

new coolant temp sensor

new crank position sensor 

cleaned MAF

cleaned throttle body

 

as you can probably imagine I’m beyond frustrated at this point. What else would cause the catalyst efficiency codes? When I clear them they return. 


 

79897B52-73B3-447C-8D0D-98FF39232272.jpeg

327F5435-EEB6-422A-8CD1-76334FAF13A1.jpeg

Edited by Nate6.0
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does your scanner do live data and take movies? the ecm monitors the 02 sensors and compares the readings from the front and rear sensors to determine cat effeciency. watching the 02 readings at different driving conditions should help determine whats going on as well as the fuel trim readings. check for a leak between the throttle body and the mass airflow sensor as well. theres been a lot of bad 02 sensors out there lately, if you bought them online or at a discount auto part they may be counterfeit even though the box looks genuine

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4 hours ago, Nate6.0 said:

Hi all,

 

I have a 2007 5.3 throwing codes for Catalyst efficiency bank 1 and 2. I have been chasing this like crazy and am at whits end…hoping an expert can help.

 

In my efforts to resolve I’ve just done in the past 8 weeks…

 

New fuel sending unit (old one rotted)

8 new plugs (AC Delco 41-162)

8 new plug wires 

new driver side valve cover (updated style) and pcv hose (to ensure no leaks)

new exhaust manifolds and gaskets both sides 

2 new cats/ y pipe (Davico $550) 

4 new oxygen sensors

new coolant temp sensor

new crank position sensor 

cleaned MAF

cleaned throttle body

 

as you can probably imagine I’m beyond frustrated at this point. What else would cause the catalyst efficiency codes? When I clear them they return. 


 

79897B52-73B3-447C-8D0D-98FF39232272.jpeg

327F5435-EEB6-422A-8CD1-76334FAF13A1.jpeg

P420 and P430 mean bad cats, not all that other stuff.  If those are Chicom cats, they do not last, usually not even a year.  But since you put new cats on and fired the parts cannon, the only other thing to replace is the ECM.  

 

When you get cat codes, it's most always the cats.  It could be the wiring or the ECM, that's it.

 

When my cats and chicom cat failed, I purchased a Magnaflow cats and y-pipe and all has been well going on four years now.

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Do these codes come back on immediately or do they take 10+ miles of driving?

 

Also if it's right away it's just coming up on the scanner and not the cluster right? Some of those codes are permanent codes and do take several drive cycles to clear.

 

 

I personally wouldn't replace the cats right away again. I'd try to space the rear o2 sensors out of the exhaust stream to see if that stops the codes from coming back.

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2 hours ago, swathdiver said:

P420 and P430 mean bad cats, not all that other stuff.  If those are Chicom cats, they do not last, usually not even a year.  But since you put new cats on and fired the parts cannon, the only other thing to replace is the ECM.  

 

When you get cat codes, it's most always the cats.  It could be the wiring or the ECM, that's it.

 

When my cats and chicom cat failed, I purchased a Magnaflow cats and y-pipe and all has been well going on four years now.


i was getting the code before I put the cats on…not saying it’s not possible that the PO cats were bad and so were my brand new ones, but it seems like a reach.

 

The parts list was for various reasons, not all for the catylist codes…it needed plugs and wires regardless, needed crank position sensor because it failed one day etc etc. i listed the parts to help fully define the situation for anyone reading. 

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1 hour ago, richard wysong said:

i did run into a car that was doing the same thing and it had a leak in the duct between the throttle body and the MAF. I was surprised fixing the leak cured the cat codes

That was a major part of my replacing the manifolds…4 bolts were broken and I suspected possible air ratio errors due to potential leaks…that and when I tried to remove the Y pipe it quickly became clear the manifolds were along for the ride 

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10 hours ago, Nate6.0 said:

Hi all,

 

I have a 2007 5.3 throwing codes for Catalyst efficiency bank 1 and 2. I have been chasing this like crazy and am at whits end…hoping an expert can help.

 

In my efforts to resolve I’ve just done in the past 8 weeks…

 

2 new cats/ y pipe (Davico $550) 

 

as you can probably imagine I’m beyond frustrated at this point. What else would cause the catalyst efficiency codes? When I clear them they return. 

 

 

 

 

Open your glovebox and look at the SPID label with the RPO codes on it.  

 

Look for any of the following codes on that label:

 

- FE9

- YF5

- NE1

- NC7

 

Or if you'd like, post a picture of the glovebox label.

 

ALSO.  Is this truck a 2007 NEW body or 2007 CLASSIC?  

Edited by newdude
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3 hours ago, Nate6.0 said:

Sure, I took this when i was confirming which tccm I needed when the 4wd went out 

 

 

 

 

 

 

Cool.  Looks like I see "NE1" for the emissions RPO option. 

 

NE1 is "Connecticut, Delaware, Maine, Maryland, Massachusetts, New Jersey, New York, Oregon, Pennsylvania, Rhode Island, Vermont and Washington state requirements" so in short, its spec'd for one of those 13 states that follow CARB vehicle emissions equipment.

 

TLDR, your aftermarket Davico cats that you posted the picture of are Federal Emissions spec cats.  At least with a GM vehicle, if it was built with California Emissions, either as a CA truck or an NE1 truck, they use CARB spec converters.  Federal cats will set P0420/P0430 codes upon installation on a CARB spec'd truck.  The cats aren't as "clean" if you will, and the ECM knows it via whatever data its monitoring for catalyst efficiency and sets the codes.  

 

You need to get a hold of either the OEM y-pipe cat assembly, or find some sort of aftermarket CARB cats for the Davico Y pipe.  It is entirely possible that the y-pipe you had on before did truly fail, or if even it was aftermarket, was causing the same issue.   

 

What's the Difference Between CARB and EPA Catalytic Converters? | Walker Exhaust Systems

 

 

Edited by newdude
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7 hours ago, newdude said:

 

 

 

Cool.  Looks like I see "NE1" for the emissions RPO option. 

 

NE1 is "Connecticut, Delaware, Maine, Maryland, Massachusetts, New Jersey, New York, Oregon, Pennsylvania, Rhode Island, Vermont and Washington state requirements" so in short, its spec'd for one of those 13 states that follow CARB vehicle emissions equipment.

 

Thank you! This is both encouraging and frustrating 😁.

 

do you think I could

1) flash the vehicle to match the non CARB cats I have?

2) space the sensors out of the exhaust?

 

if replacing cats is my only option so be it, but figured I would inquire about all options before proceeding, especially if there’s even the slightest chance that the CARB cats would not eliminate the codes. 

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On 11/21/2021 at 12:02 AM, newdude said:

TLDR, your aftermarket Davico cats that you posted the picture of are Federal Emissions spec cats.  At least with a GM vehicle, if it was built with California Emissions, either as a CA truck or an NE1 truck, they use CARB spec converters.  Federal cats will set P0420/P0430 codes upon installation on a CARB spec'd truck.  The cats aren't as "clean" if you will, and the ECM knows it via whatever data its monitoring for catalyst efficiency and sets the codes.  

 

When ordering my cats, I completely forgot that my truck has California emissions.  So it has Magnaflow federal cats and y-pipe.  I emailed Walker and Magnaflow and others back then and received no response as to what the differences might be between CARB and Federal cats.  No lights after four years and 50K miles.

 

As an aside, I've always wondered why a California car was spec'd and shipped to Pennsylvania and then sold in West Virginia and now I know, thanks!  

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