When I checked engine codes I was told that either my catylitic converter was going out or my o2 sensor was on its way out. Are there any ways I can test to see which is going out on my own -- or how do you suggest getting it checked. I was thinking take it to a muffler/inspection shop and have them check the levels (exhaust) with a probe ...if they were below what the sensor would consider normal I would know the sensor was going out.

Any Ideas?

 

You have 1 O2 sensor after each cat right? (my '95 doesn't have these so I am not sure). All you need to do is swap the left and right after cat O2's. Then you clear the code. When the code comes back, if it is on the same side as before it is the cat. If it is on the other side, it is the O2 sensor. There might be an easier way, but this will work.

Dustin

 

i hate that code.

change them both!

 

I talked to my dad about this one....(he bought it brand new in '97 and passed it to me ) and for some reason he is worried about back pressure with putting a different cat on -- I dont think I have to worry about it with some of the things the guys do around here.

He's just one of those guys I guess -- he always kept the car in awesome shape and kept everything running perfect...but he never changed anything. To say the least, he wasnt a fan of my exhaust cutout. Everyone else loves it though

 

Get the cats out all together and get a y-pipe. My dad and I put one on mine this weekend. Much better sounding.

 

Not cats and no muffler....I dunno about that. My friend has a LT1 SS without cats, but he has borla and it's more raspy than I would want.

I like the way my car sounds, I just wanted to know if anyone knew any other way to test which one it was (o2 sensor after the cat, or the cat)-- I dont want to kill $60-70 on the sensor then have to buy a new cat on top of that.

 

get rid of the cats for more horsepower and get the 02 sensor simulator to keep the SES light off. that back 02 sensor doesnt do anything important anywayz.

 

Dustin is right on. The code you're getting will tell you "Bank A Sensor X"

If A=1, it's a driver's side sensor
If A=2, it's a passenger's side sensor

If X=1, it's a pre cat sensor
If X=2, it's a post cat sensor

So, if you're code was reading Sensor 2, then just swap the post cat sensors and clear the codes (disconnect battery for 5mins). Then drive normally until the code comes back.

If the code changes banks, then it's the sensor. If the code stays on the same bank, it's the cat.

Thomas.

Oh, by the way, I'll be in Kingwood this weekend (visiting in-laws) and I do have an extra post cat sensor in my garage. If you need it, let me know before 4pm tomorrow and I'll bring it with me.

 

I just had it rescanned and there were 6 codes! (it came on after my last inspection and I was due for inspection in July or August ) 2 of them were duplicates, so there were only truly 4.

P0102 - MAF
P0400 - EGR
P0420 - Cat System Effiency Below Threshold [Bank 1 - Cylinder 1]
P0430 - Cat System Effiency Below Threshold [Bank 2 - Cylinder 1]

When he looked up the MAF it said to have it tested, so I'm going to do that tomorrow.

For the (EGR, O2's) others, the auto-guy suggested to take the sensors out and just clean them (with say choke cleaner or brake cleaner) then try them again.

I thought the cat came after the pipes Y'ed into one My friend said his 97 has two, but he thought they were one after another. Is anyone for sure what the setup is on a stock 97 Z28? I migh just have to look under there tomorrow and check what I can see.

So, from what you said...the O2 sensors that are 'bad' are the ones on either side of the exhaust manifold?

Thanks a ton,
Josh Lyon

 

A stock '97Z has 2 cats: one of them is bolted directly to the driver's side manifold (Bank 1), and the other is directly underneath the passenger's feet (Bank 2).

Each exhaust manifold has an O2 sensor screwed into it. The cats are built into the factory 'Y' pipe, and each section of the 'Y' after the cats has an O2 sensor in it.
This give you 4 O2 sensors total: one in each manifold before each cat (Sensor 1), and one after each cat (Sensor 2) -- all this is before the 'Y' comes together.

The 'Y' pipe then comes together and connects to the cat back system .... which is basically a pipe leading back to a single muffler with dual tips.

I don't recognize the codes you posted. I had a bad O2 sensor recently, but the codes I pulled were different and stated "Bank 1 Sensor 2" (Driver's side post cat).

I don't think you have an O2 or a cat problem with those codes, but I really don't know. I can tell you that whatever your problem is, it seems to be affecting both banks. Maybe someone else can chime in with a little more info for you.

What kind of mods do you have, by the way?

Thomas.

Oh, and I wouldn't recommend cleaning the MAF with choke cleaner or brake cleaner! If you're going to clean the maf, use rubbing alcohol and Q tips.

 

if your having MAF and EGR codes, I wouldnt go investigating the 02s yet. If the MAF or EGR is bad, you will be getting incorrect fuel ratios and this will affect other things like 02s and crap. I would clear the codes and wait till the light comes back on. As soon as it comes on, check the code out and fix it. then clear code and repeat.

sometimes one bad sensor can create false codes.

 

I didn't plan on cleaning the MAF, just the EGR and O2's, but thanks for the heads up. Thanks again for all the info ya'll have provided me.

PS - I actually recently moved to Austin (in August)...I just havent updated my profile. I live just North of Roundrock -- where are you at?

 

Nothing big -- the things that most people here have in their sig that I dont put in my sig - I have 'em (ie. wires, etc). No engine mods...unless you count upgrading when things break lol - That's a fun list (Water pump, Heater Core, Harmonic Balancer, etc, etc.) I have an exhaust dump (cut-out), K&N, and that's about it

I'm trying to decide what I should get myself for christmas though -- 1.5" or 1.8" drop, tint, stealth 10" sub, etc.

 

I'm actually in Leander, just north of Austin.

Any luck correcting your codes? I'm curious so see what's causing them.

Thomas.

 

No...not really any luck in correcting them. I went back the next day to get my MAF checked, but they aren't capable of checking one off of a '97 LT1 for some reason. They failed to tell me this until after I double checked with the autozone guy that they could do it and took off my MAF in the dark and brought it inside.

All the hoses to the EGR look fine and when I push on the diaphragm it moves with no problem. I just moved to Austin recently, like I said before, so I have to find my voltometer to check the MAF wiring harness.

I'm just really hoping there was just a domino effect of sensors. They're all linked closely in some way, so I'm starting at the beginning of my line of dominoes and testing one by one.