Just recently bought a 2009 cobalt LS with a SC installed. Right before he sold the car to me the seller installed a ZZP catless downpipe.

The codes that are popping up are:
P0036
P0054
P0141
P0148
P2440

I know the first three have to do with the Bank 1 sensor 2 o2 sensor. I have had a trifeca tune to get rid of the codes, but no luck.. I had the guy tune my car three different times deleting codes and flashing but these codes refuse to go away. Both o2 sensors on the downpipe are stock bosch sensors.

This has become the biggest headache i have had with the CEL. Can anybody help figure this thing out?

 

You have no cats, so your o2 sensor is reading the wrong voltage. You either need a cat welded on or you need an o2 simulator so the computer is reading it "correctly"

You can clear it and tune it all you want, as soon as it reads it again the codes will pop.

And since you're supercharged I would fix this ASAP because you're just dumping fuel

 

2 solutions.

a) retune and delete the sensors

b) cat



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Wouldn't deleting the sensor not do you any good though

 

I just ordered a o2 simulator from tougefactory.com. I'm ready for this to be over with, ill keep you guys posted.

 

Let me know if it works I still haven't bought one lol

 

the car isnt tuned already for a catless downpipe?
or did previous owner put it on AFTER he tuned. because if previous owner installed the catless dp AFTER he was tuned for SC than id just get a tune for the downpipe to encorprate everything better.

 

^^ Yes

 

get your tune updated for the downpipe

 

I'll contact the tuner and have him do that as well ^^

 

You also might need to check the oxy sensor on the exhuast manifold your last two codes are regarding fuel pressure and the secondary air system.

 

Most those codes are for downpipe. Don't use bosch sensors the ones I got from GM directly were not bosch. Get your sensors figured out and use a defouler,worked for me! If its 2.2 supercharged more than likely secondary air injection is not hooked up!

This is what I found for P2440
http://www.fixya.com/cars/t9547804-c...411_p2440_mean

 

I installed the o2 simulator today. Tomorrow ill check out the oxy sensor as well as the SAI system. My car 's fuel air ratio is going back and forth from 18 all the way to 11.8 during idle after installing the 02 simulator and resetting the CEL. Before it was approx 14.7 afr

 

Problem solved. Had a wideband installed in the header and connected the rear o2 electrical connection to the front o2 sensor electrical connection, leaving the rear o2 electrical unplugged, thinkin the rear o2 delete tune would resolve it. I uninstalled the wideband and installed two denso sensors (with the rear o2 sensor delete tune) and no CEL's as of 100 miles so far

 

Did you use the o2 simulator?

 

No o2 simulator needed