On my 97 Z28...guess I need new cats. Is there anything I can do to avoid being raped by the dealer for new cats? I'm already over the 80k Emissions warranty... Are Catco's cats 50 state legal?

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My 97 Z just threw this code last week too
The wierd thing is that when I reset the PCm to erase the SES light, it would pop up again within a few miles. Then yesterday, I noticed my battery terminals were REALLY loose. So I tightened them up, and the code hasn't showed up in over 50 miles. I know it doesn't make sense that the terminals being loose woiuld throw a code, but I don't know why else it would come on all day for a week until I tightned them, and now its gone
The good thing is that I am at 79k right now, so I can get it fixed, another good thing is that I am taking my cats off and deleting them, so I won't have to do this anyway
But I am interested in what this code is cuased by!
Good luck!

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TONEZ28 - 97 Black Z28 A4 : 270rwhp/290rwtq
Mods : K&N CAI-Flowmaster-TB Bypass-Airfoil-160 Stat-Cutout-
!MAF Screen-Manual Fan Switch-TransGo Shift Kit-BFG DR's (track use only)
(373's and Hooker LT's collecting dust)
Appearance : 01' z28 Chrome 5 Spokes-GTS Blackouts-Billet Grill-
Orange Reflective z28 & Bowtie Overlays & Camaro Letters-Orange Tint
Best E.T. : 13.64 @101.50 w/ 2.04 60'
w/ Drag Radials : 13.56@100.80 w/ 1.97 60'

[This message has been edited by sfGi8nt (edited July 23, 2002).]

 

doh! I wish it were that simple for me. But I just got a pretest to diagnose from my friend who works at a smog station and I failed miserably. So it does indeed look like its bad cats... either that or bad o2's and the car is over compensating!

 

Well you know how I said the SES light would go on about 3 miles after I reset it? And then when I tightened the battery terminals, it went away for good.
Well not for good, becuase it came back on after 100 miles!
So it is back, and it looks ugly!
Now all I have to do is get these Long Tubes installed.
But if anybody else reads this, would it be a smart idea to go in and get this taken care of under warranty (Im pretty sure the cat system has an 80k mile warranty) so if I ever decide to use my cats again (why would I?) but just to be safe, or even to sell it?
Maybe I should do this...

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TONEZ28 - 97 Black Z28 A4 : 270rwhp/290rwtq
Mods : K&N CAI-Flowmaster-TB Bypass-Airfoil-160 Stat-Cutout-
!MAF Screen-Manual Fan Switch-TransGo Shift Kit-BFG DR's (track use only)
(373's and Hooker LT's collecting dust)
Appearance : 01' z28 Chrome 5 Spokes-GTS Blackouts-Billet Grill-
Orange Reflective z28 & Bowtie Overlays & Camaro Letters-Orange Tint
Best E.T. : 13.64 @101.50 w/ 2.04 60'
w/ Drag Radials : 13.56@100.80 w/ 1.97 60'

 

Anyone have any clue if this could mean bad o2's?

The car tested rich when I went in for a smog check. Yet my fuel mileage seems to be fine (28mpg on a 500 mile trip each way). The exhaust has always smelled a bit rich though. Even before the SES popped up.

If it is the o2's should I replace the front or rear o2's first?

 

If you 1) have the code, and 2) your car failed emissions for high HC's, and 3) you can smell fuel, most likely it is the cat or cats. You could be getting excellent fuel mileage and the engine could be running right at the prescribed 14.7:1, but if the cat(s) are not working, there are unburned hydrocarbons (= gasoline) leaving the system that is not being cleaned up by the cats. This is one of the purposes of the cats... to combine the small amounts of unburned HC's with the small amount of residual oxygen to produce a cleaner exhaust.

If you only got the code for one bank of the engine, switch the after-cat O2 sensors. If the problem stays on the bank where it was, it is a bad cat on that side. If the problem moves with the sensor, it might somehow be related to the sensor.

A complete scan, with long term fuel corrections for all cells with also help diagnose the problem.

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Fred
94 Formula A3+1: 381/TH400+OD/N2O

Advanced Tech Posting Guidelines
Detailed Mod's List
11.513@115.59 on motor; 11.162@127.67, 1.643 60' on a 125-shot. Going with a 275-shot this year

 

Aaaargggg I hate to say this but "me too"

What kind of equipment do I need to do this fred? And what kind of anomolies should be looked for? The code only gets thrown for me when I am cruising at low RPMs in 6th gear.

Thanks

 

I have the same issue, P0420
So I am gonna go switch the sensors now and see if the code flips sides.

 

Holy mother of old posts Ron!

 

oops, sorry I was doing a search for it

 

Yeah i think i am throwing that code also, i smell gas, but i also had a purge solenoid code and im about to change that, but i have a MAC header and high flow cat system, does anyone think that one of my cats could be bad?

 

Actually I had mine in for a fuel pump change, they checked out the 420 code and said it's a result of my fan switch. They cleared the fan codes and it went away. Now I just have to put in the resistors I got today and no more 420, 1641 or 1642 codes.

 

The use of a scan tool greatly reduces guessing. I bought an AutoXray instrument and it has reduced my errors in troubleshooting. I hate buying parts I don't need. With the aroma of gas, failing the smog test etc. it's a good bet for the cat replacement as long as the O2's integrity can be verified. That code means that the PCM has determined that the oxygen storage capability of the cat has degraded below a calibrated threshold, therefore failure of the emissions test.

 

I just fixed my fan switch and no more SES light and no more 420 code either.

 

Sorry for dredging up an old thread but I thought it better than starting a new one. Ok, I have the P0420 code. SES started up yesterday on the drive back from work on my 97 with 83,500 (out of emmisions warranty) miles. Car has no exaust mods except for a cat back... I was just quoted $500 parts and labor by an exaust shop for replacing both cats. They said they would not reccomend only doing one. Could anyone advise if that makes sense? Is that price good? I don't have a code reader so I had it pulled at Autozone. I don't know if it makes sense to replace the o2 sensors this weekend just in case. Even, if it is the cat and the 02s are fine, does it still make sense to replace them (they are original?)

Thanks for any feedback....steve c