Hi all i have an 08 cobalt ss turbo with 95k miles. Was running fine a few weeks ago. I previously added a catless downpipe with no o2 sensor a year ago. But it still ran fine. A bit rough on startup but ran great when warm. Have a k&n intake so I get the p0100 code all the time. But a few days ago I got the p0036 plus p0300 ... p0301... p0304. So all 4 cylinders had misfires. I cleaned the maf with maf cleaner and the misfire seemed to go away but still the p0306 code. But no more cutting out or hesitation. I just drove it for 10 min. But will try longer run later. Is it the other O2 sensor near the turbo thats bad? It looks like a bitch to get it out. I wonder if I should also put back the 02 sensor in the catless downpipe if thats possible? Thanks!

 

P0036 was for the O2 sensor in the downpipe. P0030 was the O2 sensor by the turbo. Surprised that Im the only one to figure that out! So that wasnt it. Probably high pressure fuel pump or something like that? Only runs bad when warm. And cuts out under load at high RPM.
Throws codes p0036 and p0100 plus p030x for all 4 cylinders on an agressive tune instead of stock tune.

 

Did you figure it put I'm having a similar issue