Tried to fix P0430, got a fist full of new codes instead!

**Thewilldog** · 09-28-2012, 04:27 PM

I've had a P 0430 code on my 2001 Z28 for quite a while now (over a year). Never caused a problem with the way the car ran. Based on research I saw here, the code was most likely due to a worn-out catalytic converter, not a high priority. Three weeks ago I broke down and got both cats replaced with a pair of magna flows I bought from another member.

http://www.ls1.com/forums/f63/help-s...01-z28-167680/

The shop that installed them cut the old ones out and welded the replacements in place rather than dealing with the old bolts. Two days ago the car started running very rough at idle. It's gotten worse since. I ran by an auto parts store and borrowed their OBD2 scanner. Here's what I got back:

P 0430 Catalyst Efficiency Below Threshold (Bank 2)
P 0151 O2 Sensor Circuit Low Volts Bank 2 Sensor 1
P 0300 Random / Multiple Cylinder misfire detected
P 0420 Catalyst Efficiency Below Threshold (Bank 1)
P 0430 Catalyst Efficiency Below Threshold (Bank 2)
P 1153 Manufacturer Contrl Fuel Air Metering

So it looks like the car doesn't like either replacement cat, and now an O2 sensor is bad? Should I assume the shop did something wrong, or is this a coincidence? Do you think replacing the O2 sensors will fix the issue, or is there more going wrong here?

Thanks.

**az gt eater** · 09-28-2012, 06:27 PM

Sounds like your front O2's got messed up. Bad. There could be actual damage to them, the wiring could be melted, or possibly unplugged. The random misfire code tells the real story. Besides it sounds like the cats arent working either. That could be because they can't keep up with all the fuel the car is dumping into the cylinders to keep it safe.Rich is better than lean. Backfires are better than detonation. And that chugging you are experiencing is mini backfires.

**pajeff02** · 09-29-2012, 03:41 AM

If the welds are not complete the exhaust could be sucking outside air in and throwing off the upstream sensors, the sensors could simply be in need of replacement (anything over 80,000 miles), there could be a crack in the exhaust also causing the issue. Just a few random thoughts.

**Thewilldog** · 09-29-2012, 06:29 AM

Originally Posted by az gt eater

Sounds like your front O2's got messed up. Bad. There could be actual damage to them, the wiring could be melted, or possibly unplugged. The random misfire code tells the real story. Besides it sounds like the cats arent working either. That could be because they can't keep up with all the fuel the car is dumping into the cylinders to keep it safe.Rich is better than lean. Backfires are better than detonation. And that chugging you are experiencing is mini backfires.

Car has 177K miles and I've never replaced the o2 sensors. There's four, right? Not sure exactly where they are. Can I just find/pull the old ones and replace with new ones if I back the car onto a couple of Rhino ramps, like replacing christmas light bulbs, or is there more to it? Bank 2 Sensor 1 is the upstream sensor on the passenger side?

**az gt eater** · 09-29-2012, 04:49 PM

Yes it is on pass side. You can just replace them. You should get a can of PB Blaster to soak them, and some anti seize to put on the new ones. You will have to do it from the under side. IF the rear ones go, it won't affect performance, just throw a light and screw you at emissions time. And second what Jeff said. Any air getting in the exhaust will bugger everything.

**az gt eater** · 09-29-2012, 04:51 PM

And if you plan on doing headers any time soon, you should get the longer o2's. They are for a 2000 vette. I think Bosch 1311's. That way when you do put the headers on, the wires will be long enough to work.

**Knight** · 09-30-2012, 06:18 AM

Originally Posted by az gt eater

And if you plan on doing headers any time soon, you should get the longer o2's. They are for a 2000 vette. I think Bosch 1311's. That way when you do put the headers on, the wires will be long enough to work.

Bosch 13111 is the part number.

At 177k, I'd replace them anyway.

**Thewilldog** · 10-02-2012, 05:59 PM

Well, as I said they cut the old ones off and welded replacements in place, maybe they didn't do a good job with it. I'll replace the passenger side sensors and see if that fixes it.

**Thewilldog** · 10-02-2012, 06:00 PM

Originally Posted by Knight

Bosch 13111 is the part number.

At 177k, I'd replace them anyway.

Same part # for both of the passenger side sensors? Or are they slightly different?

**Knight** · 10-02-2012, 06:12 PM

They're all the same #.

**Thewilldog** · 11-23-2012, 05:07 PM

Just to confirm, all 4 O2 sensors are the same, i.e. there's no difference between left, right, up stream or down stream, correct?

**Knight** · 11-23-2012, 09:23 PM

Correct.

**04yellowjacket** · 11-26-2012, 10:38 AM

i am sure they did a good job on the cats. when you have that many miles on a set of 02's and then start having more gasses pass by them, the old 02's will not read right. if you put on longtube headers the car will need a tune to get all you can. but if other mods a in the future do them all and then spend the money for one dyno tune session. And if you can find someone who can use hptuners, they can deprogram the front two sensors. just the back two will only be necessary for the car to run right. this is what they did on my gto. no problems in over 4 yr and only one retune checked, no recalibration needed. a good tuner will get you that kind of service.

**35th-ANV-SS** · 11-26-2012, 07:56 PM

Originally Posted by 04yellowjacket

i am sure they did a good job on the cats. when you have that many miles on a set of 02's and then start having more gasses pass by them, the old 02's will not read right. if you put on longtube headers the car will need a tune to get all you can. but if other mods a in the future do them all and then spend the money for one dyno tune session. And if you can find someone who can use hptuners, they can deprogram the front two sensors. just the back two will only be necessary for the car to run right. this is what they did on my gto. no problems in over 4 yr and only one retune checked, no recalibration needed. a good tuner will get you that kind of service.

Correction. The front O2 sensors are what control engine parameters such as fuel delivery. The rear ones have no effect on engine performance. The rear O2's only monitor catalytic efficiency.

**Thewilldog** · 11-30-2012, 01:20 PM

I haven't tried to replace them yet - looking at O2 sockets online. Has anyone used the Lisle 12100 Oxygen Sensor Socket? I'm wondering if it will fit in the underbody of the car.

Lisle 12100 Oxygen Sensor Socket : Amazon.com : Automotive

**Blue28** · 12-05-2012, 09:53 AM

If you have enough room to use a adjustable crescent wrench then that will work just fine to.

**0rion** · 12-05-2012, 09:00 PM

the codes you show there ( 1153 is a switching code by they way) are your drivers side front and both rears. I would replace both fronts with 13111 sensors and call it a day at that many miles. I wouldn't bother with the rears.....I would send the pcm to frost to get a tune and have those rear codes turned off.

**04yellowjacket** · 12-06-2012, 04:15 AM

very wrong 35th. i know this on my car. i helped my tuner cut my front two off, as he deleted them out of the tune. we only put the back one's in the headers. if that was not right, it is funny i have gone 4yrs without having any retunes or codes. and my gto still gets 25 to 27 on the hwy. has for 4 yrs since i put in my cam. i lost a couple of mpg's but thats normal. maybe the camaro is different than the newer gto setup. but i use the back two.

**04yellowjacket** · 12-06-2012, 04:24 AM

you mention catalatic effecience. my cats were mounted about a foot behind the stock manifold. the front two 02;s were there to read them, and i have not had cats since my header installation. i guess gm put the cats far behind the manifold collector on your car. Oh year. my 99 chevy pickup had the cats in the same place as my gto. my sone had a 01 trans am that had them in the same place. you have precat 02's, what i deleted. and after cat 02's. what i kept.