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99 Saturn SL2 Trouble showing p 0420 code


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stullis24
User

Aug 30, 2012, 5:44 AM

Post #1 of 25 (5795 views)
  post locked   post icon 99 Saturn SL2 Trouble showing p 0420 code  

I own a 99 Saturn SL2 SOHC. Friday, the SES light came on, Went to advanced auto and they said P0420 code came up so Sunday I changed the Main O2 sensor on the cata because it looked rusted and fused to the muffler but the front looked brand new so we didnt touch it. On the way home light came back on so I turned around and went back. OBD showed same code. Reset. Yesterday was down to 1/4 tank gas, put in bottle of Lucas Complete Fuel System Cleaner and small bottle of Lucas Fuel Conditioner w/ Stabilizer per Saturn Of Cary Mechanic recommendation. On the way home, (about 5 miles) turned on AC, SES light came back on almost immediatly. Shows same p 0420 code. What is going on? Cat bad? Muffler? HELP! Please!

Thank You, StephanieFrown


(This post was edited by stullis24 on Aug 30, 2012, 5:51 AM)


Hammer Time
Ultimate Carjunky / Moderator
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Aug 30, 2012, 6:08 AM

Post #2 of 25 (5779 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

I don't know where you're coming from with all that stuff, especially the "mechanic in a can".
PO420 is nearly always a bad Cat.



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Tom Greenleaf
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Aug 30, 2012, 6:19 AM

Post #3 of 25 (5765 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

Sad note on the rust and this situation: If corrosion of an O2 primary (front) sensor is causing it not to operate that's a problem. Just removing one can cause damage to pipe or if right on converter be trouble. Careful what places that read codes suggest for the fix but rather take the info for the real needed fix. If free code readings that's nice but clearly it's to sell parts to me anyway.

Easy with fuel solvent fixes. Some and not many can help for prevention but not likely to cure things. Rust isn't going to be fixed by any magic in a bottle. Some can make things worse so generally avoid that.

Yep - have had to replace perfectly good stuff because of rot from the outside!

T



stullis24
User

Aug 30, 2012, 11:46 AM

Post #4 of 25 (5736 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

That is what a mechanic at the Saturn place in Cary NC told me to try. He said that maybe something in my lines was clogged preventing the airflow to the sensors. I dont think he necessarily meant it as a "mechanic in a bottle" so to speak, because I told him I am on a fixed income because I am disabled and really didnt have 600 dollars to get a new Catalytic. I wanted to know what I could try that would be the cheapest way out. As far as the rust goes, I thought that was because I donot have a splash guard or whatever it is called and when you drive in the rain, car gets wet especially underneath. So I thought that was where the rust came from. Sorry, I am dumb when it comes to the mechanics on a car. All of it looks like greek to me. You could probably tell me, and yes it has been done before by my grandaddy, to put black pepper in the radiator to stop it from leaking, and I did do it, when what it really needed was a complete flush and a new L hose. Only because as far as the mechanics and running of a car go, I am dumb.
Ok back to your post HAMMER TIME, Is there a way to check the CAT to make sure it is working properly? Kind of like you check an alternator or battery? Or do I just need to find a way to buy a new one?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 30, 2012, 12:22 PM

Post #5 of 25 (5729 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  


Quote
Is there a way to check the CAT to make sure it is working properly?


That is what your computer is doing for you. The conditions have to meet a whole series of criteria for it to set that code. I have only seen a false code once and that was a broken exhaust pipe right in front of the converter fooling the computer.

Saturn has been out of business and all the dealers closed a good long time ago.

Statements like this make it easy to understand why.


Quote
That is what a mechanic at the Saturn place in Cary NC told me to try. He said that maybe something in my lines was clogged preventing the airflow to the sensors.




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Tom Greenleaf
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Aug 30, 2012, 12:32 PM

Post #6 of 25 (5725 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

Stephanie - There is a before and after O2 sensor in the system. One before converter, one after. They mount (screw into) the pipes that originally (best for replacement too) was one piece and some bucks.

Typical sensor looks like this with the wire(s) and plug in....

The whole converter pipe should look like this with a ''Heat Shield" spot welded which is for not letting things get hot more than protecting it but looks like this....


You could test that the flow is adequate or correct. If the sensor(s) are no good alone would set off a code. First or the one before the converter makes decisions that will be a problem and the second is making sure it is all doing its thing properly. The wires at connector or right at sensors can rot, fall off or not make a connection OR the sensor if bad itself a problem. Bad front one can ruin a converter. If the sensors even if good and pipe is bad they can be like welded in and wreck threads so could end up with the whole bunch of things associated with it.

Problems of operation and or if they are intact at all via rust/corrosion problems are just that - problems. Not cheap stuff. A universal cheapo converter could be rigged in but wont fix bad sensors and probably wont last well either.

Whatever splash shield you are missing could be very necessary for exterior of things for water splashing on near red hot parts that don't like that. You may mean the heat shield?

Rock and hard place to fix this cheap as parts aren't cheap and may not be the whole fix. You need to trust the tech with what he or she can see as well as test for the repair and look into what might have caused it too.

It stinks and isn't free for parts even if labor was free. No magic cheap fixes for this and nothing like a little pepper in a radiator like you said that did work but also causes problems for that way of fixing things.

Worse is being late to fix many things here and there just makes the real fixes much more $$. I believe in trusting the vast majority of techs/mechanics out there and have to as they are looking right at things, we are not,

Tom



Tom Greenleaf
Ultimate Carjunky / Moderator
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Aug 30, 2012, 12:35 PM

Post #7 of 25 (5722 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

To add: In finding those pics - did notice some stuff was NOT available! Yikes - makes it a nightmare depending on just what. Hammer's reply got here first while I was looking at the set up......

Tom



(This post was edited by Tom Greenleaf on Aug 30, 2012, 12:35 PM)


stullis24
User

Aug 30, 2012, 12:37 PM

Post #8 of 25 (5717 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

I know but there are still places that are qualified to work on them which the one I use is Hendrick AutoMall in Cary NC. Here is the address and phone so as you can see I am telling the truth that they still do.... Saturn of Cary

(had to edit out shop's info - they may not want wide open exposure to the web and not allowed on this open site)


(This post was edited by Tom Greenleaf on Aug 30, 2012, 12:58 PM)


stullis24
User

Aug 30, 2012, 12:40 PM

Post #9 of 25 (5716 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

The top picture looks like the one on the Cata that we replaced. The bottom picture is the front sensor under the hood that will be replaced tomorrow. That way both sensors are new even though the one under the hood looks brand new, we will replace it just to make sure.


stullis24
User

Aug 30, 2012, 12:55 PM

Post #10 of 25 (5711 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

Thank you all for your help. I will try the front sensor tomorrow and if it doesnt work then I will have to get a new cata. I know last year when I had my ALT replaced they told me that underneath the muffler was rusted and did have a small hole in it where it looked like the muffler had been bent. Which is probably true because this car was in an accident beofre I bought it and they replaced the front end. So I do have a "Salvaged" title. The muffler could have been bent when whoever rear ended the other car. So in light of that, I do probably need the whole muffler system just so that I wont have this issue with the cata anymore. Does a cata come with the muffler system or is that seperate? I did find a few second-hand 99 Saturn Mufflers on e-bay for like 2-300 but if I go that route, I would want brand new. So I will also check Advanced tomorrow to find out the price for all. It will probably be October before I have the extra money to buy all, I just hope it lasts that long and doesnt leave me and my 3 year old baby stranded. One person told me that it wont leave me stranded but may not go over 35 mph if it does go. I just hope that was the truth. But then again, so far as some of the post I have read on here, AutoZone doesnt have a good advice. For some reason I do trust what Hammertime and Tom are saying. Just a feeling. I think they know what they are talking about. Thank you very much........


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Aug 30, 2012, 1:08 PM

Post #11 of 25 (5706 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

Had to edit out your repair place info both because not really allowed and they may not want exposure here on an open site.

Yes - There is more to exhaust system than just converter as a pipe assembly and sensors are separate. The after all that could be made up custom and proper or should be available.

Right on with the parts outlets. I do use their sites for pictures of parts and an idea of costs. That's where it ends unless "parts" places are going to fully diagnose and do the repairs and stand behind it. Yes - some of the super chains do install parts and dealers would like to use their own parts but being a Saturn is a problem as we know.

Parts outlets and repair shops are generally not the same thing. Advice from the dog on the meat wagon about who should get the meat kind of thing! Part stores do not or should not choose your course of action - a mechanic should,

T



Hammer Time
Ultimate Carjunky / Moderator
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Aug 30, 2012, 1:24 PM

Post #12 of 25 (5698 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

I'll say it again. This is not an O/2 sensor problem.
The computer is a little smarter than that.

In order to set this code the rear O/2 has to mirror the front O/2 which would indicate the exhaust is coming out the same way it went in and was not chemically changed. That means both sensors will be simultaneous and identical with the thousands of up and downs of the voltage. Restriction in the Cat has nothing at all to do with this code so don't look for that either.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



stullis24
User

Aug 30, 2012, 1:44 PM

Post #13 of 25 (5693 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  


In Reply To
Had to edit out your repair place info both because not really allowed and they may not want exposure here on an open site.

Yes - There is more to exhaust system than just converter as a pipe assembly and sensors are separate. The after all that could be made up custom and proper or should be available.

Right on with the parts outlets. I do use their sites for pictures of parts and an idea of costs. That's where it ends unless "parts" places are going to fully diagnose and do the repairs and stand behind it. Yes - some of the super chains do install parts and dealers would like to use their own parts but being a Saturn is a problem as we know.

Parts outlets and repair shops are generally not the same thing. Advice from the dog on the meat wagon about who should get the meat kind of thing! Part stores do not or should not choose your course of action - a mechanic should,

It's fine. Kinda figured one of you two would take it off for me. Just wanted Hammer and Tom to know who told me that and it wasnt Autozone or Advanced that told me to use the fuel additives and to wait until I was at a quarter of a tank so it would be more concentrated. However both advanced, autozone, and my mechanic friend that installed the main o2 on the rear of the cata was showing the same p0420 code and advanced did give me a printout of what that code means from off of the OBDII codes site. And it does mention the main o2 sensor. I guess I should have known though since I did own a Saturn before. Nothing about a Saturn is an easy fix! The only reason I wanted another is because I feel they are very safe and I had just had another baby so wanted something safe for her.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Aug 30, 2012, 2:33 PM

Post #14 of 25 (5682 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

Yea - Whole thing isn't a very 1-2-3 game. Take good parts folks, good techs to know which parts and install them, lots of code reading on 96 and up models that doesn't mean exactly what to do or replace but what the problem area is.

Then there's why it all needed anything and if not doing enough could just wreck new sensing items (O2 etc) and over burdening a converter can kill a good one.

Exhaust: Everything from the manifold at the engine, nuts, bolts, gaskets, sensors, shields, pipes, converter, clamps, hangers, a muffler - some more than one, tailpipes some with a cute chrome thing. Be glad it isn't a Jaguar or something like that!

The edit: We all volunteer here period. Site gets the pennies from the ads. Links to even a personal shop of yours would be OK but it's open web forever archived. If you really needed or wanted more info click on the person's user name and see if they allow private messages not needed for this.

This stuff with a car is really somewhat in order for now an older car. Cars are an expense no matter what you do. Smile - I'm caulking all over my house and checking in and out of caulking so that's next and the damn stuff that used to be 2-3 bucks is now close to 6-10 dammit.

If one or more of us isn't around for follow-up someone should be reading our crap if it goes on too long. Good luck with the fix and have a safe ride for your children,

Tom


Hammer Time
Ultimate Carjunky / Moderator
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Aug 30, 2012, 3:00 PM

Post #15 of 25 (5670 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

Let me clarify something. Do not PM experts asking questions about your car. That is not what PM is for. All these threads are archived and searchable for other people to read so all responses need to be included in the open forum.



Quote
advanced did give me a printout of what that code means from off of the OBDII codes site. And it does mention the main o2 sensor.


Hey, it's your money. If you are determined to throw it away, by all means go ahead.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



stullis24
User

Aug 30, 2012, 5:16 PM

Post #16 of 25 (5660 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

Ummm we did replace the main o2 on Sunday and my light is still on. That was why I turned to you guys, because I do not want to waste any more money. I am asking for help or other options on what to do next or if anyone else has had this problem. I did not ask for a sarcastic remark. Maybe you didnt mean it that way but I am sorry that is the way I took it.


Hey, it's your money. If you are determined to throw it away, by all means go ahead.



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 30, 2012, 5:43 PM

Post #17 of 25 (5650 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

That's OK, That's the way i meant it. My shop changes 3 or 4 Cats a day. I told you that an O/2 isn't going to correct that code but Advanced auto parts says it can so go right ahead and listen to Advance if you wish. They get to sell a ton of sensors with their advice but they don't correct too many problems.


Quote
The top picture looks like the one on the Cata that we replaced. The bottom picture is the front sensor under the hood that will be replaced tomorrow. That way both sensors are new even though the one under the hood looks brand new, we will replace it just to make sure




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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



stullis24
User

Aug 31, 2012, 1:08 AM

Post #18 of 25 (5638 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

Hammer, That was before I checked with you guys. We changed it on 8-26 and was still having same problem, that is why I came here last night asking for advice so I wouldnt waste anymore money. I am taking it to Precision or Midus tomorrow. Havent decided which yet. Did find another person on the Midus site that has a Saturn exactly like mine, same year, model and color and all and read their comments and they said that their was doing the same thing with the weird CES light and turned out to be a known faulty signal with the computer (taken directly from their comments:"Apparently it’s some kind of bug with the computer and it should only happen in the winter when it’s cold. Except that it doesn’t") so I am hopeing that is all it is. I will post when I get back tomorrow from which ever I go to to get the exhaust system checked and let you guys know What they say. I dont think it is the Cat though because I did get another friend of mine who just had to replace his Cat to look at it and listen and he said that it does sound normal and smooth running. Not garglie or loud or rough like a bad CaT. Although when we were out there with the car running, there was a sparatic metal tapping sound that happened a couple of times from the area where the gas tank is. It didnt happen at set minutes or seconds, it was off and on. Not sure what that is but WILL find out tomorrow. I am hoping it was just because I have those 2 lucas' in it and the fuel pump or whatever is having a fit but I dont know. Thanks Guys, you have been helpful and Hammer.....you too, even though you may need a cup of coffee or a nap! I will recommend your site to anyone who is having car troubles so that maybe you guys can help them. I will talk to you tomorrow with I hope a good or cheap (knock on wood) report.

In Reply To
That's OK, That's the way i meant it. My shop changes 3 or 4 Cats a day. I told you that an O/2 isn't going to correct that code but Advanced auto parts says it can so go right ahead and listen to Advance if you wish. They get to sell a ton of sensors with their advice but they don't correct too many problems.


Quote
The top picture looks like the one on the Cata that we replaced. The bottom picture is the front sensor under the hood that will be replaced tomorrow. That way both sensors are new even though the one under the hood looks brand new, we will replace it just to make sure




Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 31, 2012, 3:15 AM

Post #19 of 25 (5633 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  


Quote
Not garglie or loud or rough like a bad CaT.


LOL, yeah, right

I give up



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
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Aug 31, 2012, 4:46 AM

Post #20 of 25 (5629 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

Just wondering, but why don't you find someone with a gas analyzer to confirm the cat isn't working?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Double J
Veteran / Moderator
Double J profile image

Sep 1, 2012, 12:06 PM

Post #21 of 25 (5583 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

We beg ,implore,beseech you to heed the Sage Advise from HT


And


Quote

Thanks Guys, you have been helpful and Hammer.....you too, even though you may need a cup of coffee or a nap!



I'm thinking DECAF!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 1, 2012, 1:59 PM

Post #22 of 25 (5576 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

She had a post here claiming the 0/2 did fix the problem which is total crap. Most of her post was just ranting on me so I just deleted the whole thing.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 1, 2012, 6:04 PM

Post #23 of 25 (5562 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

 
DTC PARAMETERS
The stage one will fail when the catalyst efficiency becomes less than 75% efficient. After stage one fails, the 50 sample test results are used by stage two. When the results of stage two are greater than the fail threshold mV (catalyst efficiency below about 70%), the MIL (SERVICE ENGINE SOON) telltale lamp will be illuminated and a DTC P0420 will be set.

Probable causes of a DTC P0420 are:
  • Exhaust system leaks between the front and rear sensors or rear sensor leaking.
  • Catalyst deteriorated due to excessive time operating vehicle with a catalyst damaging misfire.
  • Contamination of converter due to incorrect sealant, fuel, or fuel additive.

IMPORTANT: A catalyst monitor test will not be performed if a fault exists in the rear or front oxygen sensor circuits.

DIAGNOSTIC AIDS
DTC P0420, once set, should remain active. However, under certain driving conditions the catalyst monitor test may pass. This condition may occur if driving the vehicle at highway speeds (high air flow) but if the P0420 is set and no exhaust leaks are found the catalytic converter should be replaced. If a misfire (P0300) is detected P0420 test will not run. Be sure to correct a misfire condition before replacing the converter.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Double J
Veteran / Moderator
Double J profile image

Sep 1, 2012, 8:24 PM

Post #24 of 25 (5547 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

Yeah you know it didn't...

I was just messing around with the DECAF thing...

Still amazes me everytime how people come here seeking FREE advise ,get it and then commence to tell you how wrong you are

And who doesnt need a nap.....I'd be all for a Siesta everyday..'Cept, i probably wouldn't get back to work...


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 1, 2012, 8:28 PM

Post #25 of 25 (5542 views)
  post locked   Re: 99 Saturn SL2 Trouble showing p 0420 code  

Yeah, she posted a bunch of crap again telling me how wrong i was. That's why I locked it. Maybe someone else will believe her nonsense but I don't want it posted here. She'll be buying a cat sooner or later.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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