Need help with check engine light (P0133 and P0153)

[12secondv6]

The check engine light come up intermittently for P0133 and P0153 (O2 sensor circuit slow response).

This never occured on the car when it was stock to slightly modified (cold air, cat back etc)

I recently had the following done:
Pacesetter long tube headers (with air and egr)
Catco 3 inch high flow cats
Magnaflow cat back
LT4 knock modules
1.6 roller rockers
mild port work to the heads - pretty much just cleaned up
New spark plugs
New O2 sensors in the headers
Front O2 sensors have O2 sensor extensions
Rear O2 sensors have O2 sims


Once the above was installed (minus the cats) the exhaust hit the underneath pretty bad.

I recently went to a local shop who installed the high flow cats and massaged/ tweaked the exhaust and the banging is MUCH less - but still occurs slightly. The shop offered to have the car back in and they said they could do a bit more to avoid the exhaust hitting the floorboards.



The check engine light/ exhaust banging is driving me nuts. I can get the banging taken care of but I am at a loss for the check engine light.

I bought the O2 sensors maybe 4-5 months before they got installed so I wonder if that may have caused something.... or maybe, could the banging have damaged the O2 sensors?

I used a scanner on the car to monitor millivolts and at idle it was VERY obvious that the millivolts were VERY slow... but they still fluctuated. As I would cruise, they seemed to fluctuate like normal readings.

Can anyone provide some help/ suggestions?

Thanks!

[JSPERFORMANCE]

Those o2 codes pretty much only come on when the sensor is getting old, it means that the sensor is communicating and the circuit is working fine it just dosent switch from rich to lean as fast as the parameters want it to.. It sounds to me like you may have got a defective pair of o2s.

[JL8Jeff]

If the new O2's were put in right when the headers were installed, then some of the crap that burns off the new headers may have contaminated the O2's. As for the y-pipe hitting the floor, mine does slightly on the LS1 as well. New poly motor mounts will limit the engine twist and might solve your problem. I wish I did them when I did the headers because it's going to be a huge pain getting in there now.

[Pampered-Z]

Originally Posted by JL8Jeff

If the new O2's were put in right when the headers were installed, then some of the crap that burns off the new headers may have contaminated the O2's. As for the y-pipe hitting the floor, mine does slightly on the LS1 as well. New poly motor mounts will limit the engine twist and might solve your problem. I wish I did them when I did the headers because it's going to be a huge pain getting in there now.

Also hear that if they used RTV on the gaskets that can kill O2s as well.

[ins0mnia24]

I got those 2 codes a few weeks ago after hitting a large puddle..
went away soon as I replaced them..

Sounds like some of you should invest in a Mufflex Y-pipe bump stop hanger