Hi All, my check engine light keeps coming on for the P0153 code, slow 02 sensor. I have replaced the pre-cat 02 sensor on the passenger side and reset the code with a code scanner as well as removed and resinstalled battery cables.

I recently had a Y-Pipe installed and Built a homemade CAI but other than not I have not done anything else. CAI intake was done a few weeks ago and the code did not appear until after y-pipe was installed. Could this be due to the rest of the exhuast being stock muffler and resonator?

Any ideas/suggestions. I really dread the idea of going to the dealer.

 

Here is some help for you, from http://www.obd-codes.com/p0153

 

Ok, no luck with resetting the computer to make the P0153 code go away. It works for a while but just comes back after 50 miles or so. Tried to do the reset today and go for emmision inspection but the computer there could tell the PCM had been reset and they sent me away for two weeks before I can have it retested.

Replaced O2, wires look good and no sign of an exhaust leak. So here I sit in the dealer waiting room paying $105.00 for them to diagnose the problem. I have not done anything to the truck besides homemade CAI and Y-Pipe so I am fully prepared for them to come back and say it is an issue with one of these two items.

I will keep you all posted but this stinks.

 

Is the Y pipe clamped or welded? Since the code did not appear until after the Y pipe install, I would start my search around that Y pipe, looking for an exhaust leak...

 

Hi Hammer,

Y-Pipe is welded and does not appear to be leaking when running.

 

Then the next place I would look would be around the manifold, specifically for broken bolts. Although it's more common on the 4.7, it does happen with the Hemi too. I'm leaning toward an exhaust leak somewhere.

I've seen a VERY free and flowing exhaust cause the code, but always when the cats are either omitted or replaced with hi-flow models. Although replacing the sh*tty factory Y is ALWAYS a good move, I just can't see only a CAI and a better flowing Y being enough to take it out of spec.

Check the wires going into the O2 as well, a nicked/broken wire would do it too.

Although I agree with you fully - it's gonna be either your home-made CAI or that Y pipe, whether it is or not. I've done the "Y" twice for myself and twice for others and have made damn near two dozen CAIs now and I've yet to see that code. Only one I've seen to date is a code for the IAT sensor once and that's because I f*cked up and it came out of the intake I made. LOL...


You gotta find/fix this one though, unlike a post-cat sensor which only generates a nuisance CEL, this is a pre-cat (passenger side to be exact) and WILL effect the way the PCM dumps fuel, effecting power and fuel economy negatively...

 

Is it possible there is an air leak in the CAI at or after the air flow/temp sensor?

 

Ok, Hammer you suspicions are correct so far. Dealer said they located a small leak post Cat on top of the exhaust pipe. Leak is so small they used a stethoscope like tool and a rubber hose in their ear to find it. Also there was a slight discoloration around the leak area from the blow-by gases. Difficult to see and get to without a lift.

Anyway, took it right back to the muffler shop and they guy agreed that he found the leak as well and re-welded the seam post Cat on passenger side as well as checked all the others for potential leaks

Code is off for now so let’s see if it comes back. Since I work at home I don't drive it a lot so it may be a few days before it comes back on, hopefully it won't.

Anyway, dealer did say even a leak post Cat could set an error on a pre-cat sensor in some cases.

 

Sometimes I know what the hell I'm talking about, not often, but sometimes...