catalytic converter bad....again.

Radiator

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I own a 2010 Lacrosse CXS with the 3.6L. I bought it used with about 6000 miles on it, and I have about 26000 on it now. I've had a couple issues with the car, but nothing too bad....had the stereo replaced due to the GPS issue. Had a seat track replaced. When I first got the car, the check engine light came on, and the dealer mechanic guy told me that I had a bad oxygen sensor...so they replaced it. Then, a few weeks later, the check engine light came back on....I was told the catalytic converter was bad....so they replaced it. They thought maybe the bad sensor contributed to the converter going bad. This happened about 2 years ago. Yesterday morning, the check engine light was back...brought the car to the dealer, and was told that I need another catalytic converter. I asked if it was the same one, but they didn't know. I use only top tier fuel, and I run premium all the time. Any thoughts on this? I am still under warranty (thankfully)...but I sure would hate to have to pay for one of these things...:eek:
 

f6john

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If they have two convertors, I'm betting that it's the second one going bad. Had a problem with my Titan and they replace one side and it wasn't long before the other side had to be replaced. Mine were under warranty too thank goodness. Emission warranty was good to 80,000 miles with the Nissan.
 

BIG ROCCO

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Failed catalytic converters are usually damaged by heat (from running too lean a mixture in the engine), or are contaminated by fuel/soot (from too rich of a mixture or an ignition miss) or oil (rings, etc) or antifreeze (head gasket, cracked head or block)
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jft69z

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Yup...there are two converters. I doubt I will ever know if it was the same one.
Does the repair order(s) say what the codes were? There may be some indication if it says something related to 'Bank 1' or 'Bank 2' codes.
 

Radiator

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The repair ticket didn't seem to specify which converter was replaced this time (or last)...however, my dealer tech assured me that it was the opposite side as last time.

The repair ticket also stated that they repaired a coolant line (or something of that sort) when replacing the converter...it seems to suggest that the line broke when performing the work. Perhaps, this was related to the failure in some way. Also, I was pleased to find out that these repairs would have been covered by the 8year/80000 mile warranty for emissions, which hadn't occurred to me...I had some concerns that it seems to be using up cats, and my warranty is about to expire. I should add that my dealer has been fantastic about repairs, and loaners...considering I bought the car used elsewhere. I hope to continue to do business with them for a long time.
 

Radiator

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2010 Buick Lacrosse CXS
My check engine light came on again...any guesses on what it might be? Its the Catalytic converter again. After talking with the service personnel, I have been told that I should not be running 93 octane fuel in my car. The car has a VVT 3.6L engine. I went so far as to get out the manual and show him that the manual states I should use 91 or better octane. They said the manual is wrong. They said that if GM wanted me to use premium fuel in the car, they would have put a sticker on the inside of the fuel door stating this, and he showed me the sticker that resides on the inside of the fuel door on a Z28.

I don't believe them. Would the customer service folks like to chime in on this? My dealer is actually telling me to disobey the owners manual by telling me the VVT engine doesn't support use of high octane fuel.
 

HotZ28

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After talking with the service personnel, I have been told that I should not be running 93 octane fuel in my car.
The service personnel is FOS! Fuel octane has nothing to do with converter failure! Have you noticed any oil consumption between normal oil changes? BTW, all customer service can do is notify the dealer of the problem and schedule an appointment for service. They have NO (0) technical experience/ability to give advice.
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Radiator

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I've never had a more frustrating conversation...when I told him about the manual, and actually got the book and showed him what it said (91 octane minimum) he said, and I quote "If it said to run diesel in the manual, would you do that?"....incredible. These guys are just the ones who set up the service and appointments, not the tech...and they all three agreed with his explanation about the octane. What a joke. Perhaps I should try to get someone at GM corporate and try to have them contact this dealership (although I don't know where to begin or who to call).

Sadly, I used to really like this dealership...and it is close by and convenient. I can't deal with these people any more...they are either lying to me, or incredibly misinformed about how an engine works.

Thanks for the response HOTZ28. Oh, and no, I have not noticed any oil consumption. As of now, I have been through 3 O2 sensors, and 2 cats (soon to be 3 I guess).
 
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jft69z

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Are you using any antifreeze that you've noticed? That will kill O2 sensors & cats.

Good luck with GM customer service too, they're not going to be much help either. Had an issue with warranty work on one of my other cars & it was a 6 week battle thru their customer service dept. It ended up at their 'executive offices' in Detroit. I figured oh boy, now we'll get somewhere......they were useless too. All I kept hearing is 'we're sorry"....

Apparently the 'New GM' doesn't need any more of my money by the way they treated a VERY loyal customer. I no longer purchase GM vehicles as a result.

Edit: You don't have any aftermarket accesories do you? Remote starters, OBDII apps with hardware that plugs into your DLC port? Sometimes there are service bulletins that mention those kind of things that can possibly cause problems with fuel management and cook convertors etc. and they will deny warranty service. (probably not likely in your case but just a thought)
 
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Merrill Crosbie

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What altitude are you at? That 91 octane requirement is at sea level. I live at 5000 ft and we can't buy 91 octane. Regular is 85, midgrade is 87 and premium is 89. So the manual isn't always right for every situation. Lower octane works fine at higher altitudes. In 1994 I bought a new Cadillac with a Northstar and only ran premium. The O2 sensor failed multiple times. Finally the service manager told me that premium fuel had more detergents that were eating the sensor. I switched to 85 octane regular and never had another problem. The next year Cadillac specifically stated to use regular fuel. Just my .02
 

jft69z

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Nowadays though they are telling everyone to use top tier gasoline because it has more detergents to keep the engines clean.

The direct injection engines are having more troubles with carbon build up now too. Now they are pushing carbon cleaning procedures to combat this. Loss of power, misfires & drivability issues are a hint that it's getting carboned up. Just read a good article on this the other day (the magazine - Motor Age- I think, is at home, but these articles below also explain it well).

http://www.underhoodservice.com/direct-injection-engines-develop-carbon-deposits/

http://www.searchautoparts.com/motorage/technicians/drivability/causes-carbon-buildup-gdi-engines?page=0,0
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Radiator

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Thanks for the reply jft69z. I haven't noticed any use of antifreeze. No after market accessories, car is completely stock. The car actually only has 44K miles on it, and generally runs well...although I can kinda sense when this issue is going to again show itself. You can notice a little bit of a rough idle for a few days before the light comes on. This time, the light came on, and then after three days, went back out, but since I had an appointment with the service folks, I went in anyway. I still have the courtesy car, which I was lucky to get since I am past the 4 year warranty...
 

Radiator

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Hi Merrill...I firmly believe that octane itself doesn't matter, the fuel will still burn when the spark is put to it. I would tend to agree that it is not necessary at altitude, because fuel is less likely to pre-detonate, but nevertheless the Variable Valve Timing of these engines is designed to make the most of the air/fuel/octane equation. Top Tier is also recommended, as jft69z mentioned, to keep the engine cleaner. It is most definitely true that I run top tier almost exclusively, which would lend credence to the detergent idea, but again, it is recommended. But, to answer your question, I am outside Orlando...about as close to sea level as one can get. While I understand that the manual is not right in every situation, this engine is marketed as a VVT. Again, it should make use of the fuel in the most efficient way possible, using timing advance\retard as required by the fuel and air available.
 

jft69z

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Do you have 91 octane available down there? Around here the choices are 87,89,91, & 93. My '11 CXL 'required' 91 octane which I tended to use most of the time. Tried 89 a few times but the price difference wasn't much so I stuck with 91. Naturally, the next year I think they bumped the HP & lowered the octane requirement, lol.

In general, there is no need to go over the required octane rating as it doesn't do anything for performance. It actually slows the rate of combustion to combat detonation. If your compression ratio & engine specs call for 91, there isn't any advantage there. Some guys here have used 89 successfully with no perceived performance or mileage hit. At any rate, if the octane is a bit too low & the engine sensors detect knock, it will pull the timing to protect the engine. Most of us won't ever feel that in the seat of the pants driving.

My Corvette & CTS-V say 91 minimum though & I always put in 93 octane & never had any problems. Granted those engines are high performance & it also says in the manual "for best performance use 93 octane".

Still, for a dealer to say the gas is cooking your sensors & cats........never heard of such a thing. It's not like you're using 110 octane leaded racing fuel.....
 

Radiator

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Yeah, we have 91 octane in some spots...but 93 mostly I believe. You can get 100 octane from a pump near the local drag strip...last I knew it was about $10/gallon for that. (I don't use that either).

I am just in the habit of putting premium in the tank. I have been told that mid-grade is a mix of the two fuels (premium and regular), and I have always felt that I would prefer to use the premium. I figured if the VVT will retard the timing for low octane, it would advance as far as possible for high octane (makes sense of course)...and certainly I don't expect there to be any harm done by using a high octane pump gas that is available at the gas station. I also have been led to believe that the detergent packages are sometimes different(better) for some brands when using the more expensive premium gas. I get the fact the higher compression engines need the higher octane to prevent the detonation issue, and there is no benefit for lower compression engines. I actually consider this when looking at motorcycles, as I have some hope of riding into Mexico at some point, and you can not count on high octane there....so no high compression pistons, etc for that.

I guess I have an issue with the guys there telling me that I am wrong for following the car manual, and that instead I should do what they are telling me. In essence, don't blindly follow what the manual says, blindly follow what I say...even though what they are telling me goes against my lifetime of experience and understanding. And as you say, the idea that using premium fuel is causing issues with O2 sensors and cats...just patently absurd in my opinion. I would wonder if they will begin telling each customer that has an issue with an O2 sensor that they should not run the fuel that is specified in the manual...or if they just want to tell me that to pacify me....or just owners of 3.6L VVT motors. He also asked if I had used E-85(to which I replied no), and he said "Good, because its not a flex fuel vehicle", which is true.

Interestingly, post #9 at this link is from a GM rep: http://www.gminsidenews.com/forums/f21/2010-lacrosse-cxs-premium-gas-not-91907/

"The 3.6L in the 2010 can run on regular unleaded (87 octane), but premium is preferred."


-Jared Duane
GM Customer Service

Oh, by the way, a good friend of mine has a new stingray, and a CTS-V as well. Couple of nice cars, truly fast.
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Radiator

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Just to close the loop here...

My dealer told me that the catalytic converter code was incorrect, and was actually due to a crossover coolant line that was leaking on a ground lug, and causing faulty error codes. He stated that this was a repair bulletin for my model buick. We shall see if this proves to be the case....
 

tomtella

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2010 LaCrosse CXL AWD
I have a 2010 Lacrosse CXL with the 3.0 engine. Bought it used with 40,000. The rear catalytic converter started acting up (check engine light popped on about every 400-500 miles, it was a PO420) at 110,000 miles. I tried replacing both O2 sensors, but that didn't fix it. Finally replaced the cat to fix the problem. Sure enough, not even 10,000 miles later, the front cat started doing the same thing (this time it was PO430). Had to replace that one, too.
In my experience with at least 15 different cars (U.S. and European) since the beginning of catalytic converters, I've never had to replace a catalytic converter. I usually drive my cars to at least 200,000 miles before retiring them. And oh by the way, I have always run my cars (including two Mercedes C-Class) on 87 octane fuel. I always do a test, running the car for a month on 91 octane and then back to 87. I have never seen any difference in fuel economy or performance in any of my cars, and, I might add, I've never had any serious engine problems either.
 

kevinande

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Have any one with these problems ever tried a tune up. I know manufacturers tell us to run 100,000 miles on a single set of plugs, but IMO it's asking a lot of out of a plug. Un-burnt fuel an excessive heat is what generally what kills CAT's. Spark plugs are a direct contributor to these symptoms. I never have and never will run 100,000 on any plug on any car despite what the manufacturer recommends and consequently have never had to replace a converter. Even my RX8 which has a reputation for eating them for lunch has been spared CAT replacement. Just my .02
 

Bradford Webb

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I have a post from a couple of days ago that is almost identical to yours. I too, was suckered into replacing the cat converter, O2 sensors (twice), mass fuel sensor and then when they told me all my shocks were leaking fluid and that wouldn't be covered under warranty, I knew they were a bunch of crooks. I too have a 2010 CXS and can tell you a couple of things. My battery was bad, with the front two cells leaking acid out of the front of the case. I'd been plagued for two years with intermittent check engine, check stabilitrack and ABS / Brake lights, plus a failed keyless push button ignition and the trunk opening itself at random. Seems like all the dealer's mechanics can do is change parts until they are lucky enough to get the right one, or they reset the computer to get the check engine light to go off for a few days, then when it comes on again, tell you it is unrelated to the thing they fixed before. When I went in to check my battery, the check engine light and service stabilitrack message were on. After the battery was replaced, no more warning lights and the car actually runs much better. So, check to see if your 6 year old battery is the culprit. As for the octane, the car's computer should compensate for low octane and that generally does not cause a cat converter failure.
 
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