Zarrex

AS the title states I recently got my Joe Z exhaust installed. About a week after having it on the car I got a P0420 code. Check engine, check VSC, dash lit up like a Christmas tree. Took it back to the shop and had them check the O2 sensors, exhaust bolts and everything. He said all looked good but the MAF sensor was dirty and it was running rich, so he cleaned that up for me and cleared the code. Everything stayed off for a week and just came back on today. I guess my question is, has anyone else had this exact same problem, and do you think it's directly related to the exhaust install, or just a coincidence and my cat is having problems?

93MSB

iTrader: (8)

If it popped up shortly after an exhaust install and since the code is exhaust related I would assume it not just a coincidence.

the most common thing ive seen is an exhaust leak causes the CEL to pop up. Was it a new exhaust system or if it was used did you purchase all new gaskets? maybe a flange is warped?

How many miles are on the car and do you know if the o2's have ever been replaced? The o2's do get lazy/worn out over time. Did they hook it up to a computer to see how the sensor voltage changed with throttle input?

Probably unlikely but perhaps it could be something that's specific to your car in your climate that the computer cant compensate for and you need O2 sims

Zarrex

I want to believe it's exhaust related, it just seems like too much of a coincidence. Car has ~56k miles and I've owned it for a year and a half

ISF2008

Bummer. I just picked up a Joe Z Exhaust as well. A bit concerned now. Where can I get new gaskets from?

Rossi

iTrader: (5)

This code is related to your catalyst. On the ISF, I believe bank 1 is driver side, as typically the first cylinder is closer to the oil cap.
Our cars don’t burn oil, the catalyst failure is unlikely. The very rich mixture might be another reason for catalyst to fail. Too much unburned gas can eventually melt the catalyst.
You might check your catalyst reading on your scanner to see if the value is out of range and by how much. Most likely problem is your driver-side downstream (secondary) oxygen sensor got dirty (clogged with anti-seize) or got damaged during the install.

Most common testing method is to swap both downstream sensors to see if the code pops up in bank two, indicating faulty sensor. If that is the case, I suggest replacing O2 sensors in pairs.

Otherwise it might be you catalyst. In that case I would start with “Italian tuneup”. Pour bottle of Techron or Cataclean in your tank with some Shell nitro+ gas and drive the car hard with some higher revs and hope it cleans the cat up. If you believe the problem was caused by dirty MAF sensor, this might work for you, however, I would have expected MAF sensor related CEL. Good luck.

93MSB

iTrader: (8)

if you have the original gaskets take them up to autozone/oreillys and they should be able to match them up.

worst case scenario, you have to take some measurements and hit the parts catalogs

Joe Z

iTrader: (10)

The exhaust doesn't cause the CEL.. The installation does..

1) The O2 sensors wiring is damaged or twisted up causing an issue.

2) The gaskets are leaking at the primary connection to the OEM manifolds.
Usually caused by mis aligned installation or damaged old gaskets..

Is this the same shop that had concerns or issues on the first go around attempt for the install ??

Eitherway you need the installation process rechecked ASAP.


If you need two new OEM crush gaskets the part number is below:







Joe Z

Zarrex

Going to pick up my car from the shop now, it was indeed the gaskets. Fixed with some muffler cement for now and will order the gaskets in the mean time. Thanks for the tips Joe

Not the same shop as the first time. Left that one and found one that I'm really happy with so far

Wh0pp3r

Ohh man, i shoudl check if i have these.