Thread: Failed Emissions Inspection (1st try)

Ok , so I went to get my car (2005 Pontiac Grand Prix) inspected so I could renew my tags. The guy connects his OBD connector and prints out a form and tells me that my o2 sensor, cat , and evap system are Not Ready. Basically I didnt pass. Ok so I need help locating the problem , I was told that I need to do a Drive Cycle. The problem im having is that the check engine light has turned on about 3 times now, everytime it is a P0420 which basically it is a CAT problem. I turn off the light with my OBD2 connector. I have speed daddy headers, hi flo cat (could be the problem) . Any help will be appreciated I need to get the parts I need to fix the problem and also I need to do a Drive Cycle.

Every time that you clear that code, it resets the monitors. And you have to do another drive cycle. My hi flow cat caused that fault but it is now tuned out of my pcm. The Catalyst will never show ready, but I can have 1 monitor show "not ready"

Ok if I buy the CAT, then have it welded do I still need to do a Drive Cycle ?? By saying " let the PCM run its diagnostics" how does the PCm know how to do that?

Originally Posted by KeithGTP03

Every time that you clear that code, it resets the monitors. And you have to do another drive cycle. My hi flow cat caused that fault but it is now tuned out of my pcm. The Catalyst will never show ready, but I can have 1 monitor show "not ready"

I have an Intense PCM and I didnt delete the cat. I believe all the codes need to show READY in AZ

I didnt delete the CAT, just the P0420 code. It doesnt trip the SES light, or show up on the test equipment that they connect to your car. I just went through this the last few years. Took me 2 years to finally get it to pass. I had two monitors showing not ready. The EGR and CAT. I reinstalled an EGR system and once it finished its diagnostics, it showed ready. But if you have to have all monitors show "ready", you may need to reinstall a stock CAT.

Originally Posted by KeithGTP03

Every time that you clear that code, it resets the monitors. And you have to do another drive cycle. My hi flow cat caused that fault but it is now tuned out of my pcm. The Catalyst will never show ready, but I can have 1 monitor show "not ready"

Then you didn't set the DTC correctly

Originally Posted by matt5112

Yes.

You can google the GM drive cycle. Follow that procedure to complete those tests quicker.

ok so you recommend that magnaflow cat? I was told that the hi flo cat was probably the one throwing the code.

This is from Arizonas emissions website

Model year 2001 and newer vehicles
may not have more than one “not-ready” monitor.

k I have a summit account which CAT is recommended to install , I believe the headers are 3"? Any suggestions, also im also replacing the o2 sensor as well what part# do I need .

Originally Posted by KeithGTP03

This is from Arizonas emissions website

Ok well I had 3 NOT READY . Evap System , o2sensor and CAT

Ah, the EVAP is the one that took me the longest to pick up. My 02 sensor picked up pretty quickly though.

Should I order this cat MagnaFlow 99009HM, also what is the part# for the rear o2 sensor?

Originally Posted by matt5112

no that one isn't that good.

order the 43009.

Cant find the 43009 on Summit anything similar?

Can't you space out the rear o2 with washers so it doesn't throw the code? I thought I read that somewhere but could be mistaken.

dsmuts i believe is talking about this... kind of interesting to see if itll work for you rather than going the rout you are already.... just an option

Why even bother? Why not get a pcm from overkillwill? If you just need to pass the obd2 computer test. Tell him your issue and your mods then get a new O2 sensor and fix the evap. Point being... Get the stupid catalytic converter codes tuned out and never worry again. I run an Overkill tune and straight pipes to just mufflers. Btw I pass every time lmao :-P

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