Catalytic Converter Issue 2010 LaCrosse CXL

kevinande

Full Member
33
2
8
Buick Ownership
Buick
My lacrosse has about 107,000 miles. I had no problems until a month after I had my spark plugs changed. I would get code P0420 I reset it and it wouldn't come on until about 600 miles later this happened twice. So in between the first and the last time i used cataclean to see if that would work. Like I said the light came on for code P0420 about 600 miles later. Now day before yesterday the code came on so i reset it. And today it came on with code P0420, P0430. Im wondering is it the Cat, 02 sensors, NGK spark plugs that were installed, Leak in the intake gasket when installing the spark plugs. Any suggestions???
The only way you are probably going to lose the code for good is to replace the converter. Clearing the code each time it comes up does not fix the problem.
 
35
7
8
Buick Ownership
2011 Buick Lacrosse
I agree 100% on clearing the code does not fix the problem. I would hate to be like others that I have read about who have replaced the cats and the code comes back. Im the third owner of my Buick but I can tell that one of the owners was not the best on maintenance. Just did the bare minimum and the other took real good care of the car. Rides like a dream Im just trying to keep it that way. I do about 25k to 30k miles a year. Im just trying to make it last.
 

trackfan

Buick Newbie
3
1
1
Buick Ownership
2010 Lacrosse
Sounds similar to the issue I have been having. I have a bluetooth OBD2 reader in my lacrosse and the app I'm using is InCarDoc. I noticed that the downstream bank 2 O2 sensor wasn't registering a voltage. This caused the upstream sensor to read higher than normal voltage. I put a new O2 sensor downstream and I was getting no voltage. Both Bank 1 sensors are working just fine. Seems like between the O2 sensor and the Computer, something is off. I'm suspecting that the wiring possibly could be damaged. Been driving like that for a year now. Fuel mileage has decreased, there are subtle acceleration hesitations that can feel here and there...
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35
7
8
Buick Ownership
2011 Buick Lacrosse
Are you saying that you had this problem more than once. Is it the brand, OEM, MFG issue? When you have them replaced did you ever get a chance to take a look to see the damage? That does not sound good at all. I winder if that guy on youtube stuff actually worked with the gallon of whatever it is in the gas tank. I can go for it.
 

Zeroboostbuick

Active member
975
212
43
S.W. Ontario Canada
Buick Ownership
2018 Regal Sportback - 2010 Yamaha R6 (track bike) Past cars: 92 LeSabre, 98 Regal, 02 GrandPrixGT
Is it me or are some these cats failing when the owners fill up with premium fuel when the engine was designed to use 87 octane ?
Might be just a coincidence.
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35
7
8
Buick Ownership
2011 Buick Lacrosse
Mine runs sluggish with anything over 87 octane. Funny thing I put $10.00 of 89 octane today, in which I have not done in months to see if it would run sluggish. And yes it is thats why i only put $10.00. But when I used the cataclean a couple months back I got up to 35mpg and I have a 3.6 FWD CXL. I got actual video
 
35
7
8
Buick Ownership
2011 Buick Lacrosse
Now I have not changed my 02 sensors or cat conv yet. Thats why I asked did you ever take a look at yours. I wanted to try the thermostat test I have been seeing.
 

Zeroboostbuick

Active member
975
212
43
S.W. Ontario Canada
Buick Ownership
2018 Regal Sportback - 2010 Yamaha R6 (track bike) Past cars: 92 LeSabre, 98 Regal, 02 GrandPrixGT
Mine runs sluggish with anything over 87 octane. Funny thing I put $10.00 of 89 octane today, in which I have not done in months to see if it would run sluggish. And yes it is thats why i only put $10.00. But when I used the cataclean a couple months back I got up to 35mpg and I have a 3.6 FWD CXL. I got actual video
I had a 98 Regal and 2002 GrandPrixGT 3800 V6 sedans N/A and both would guzzle premium fuel like a dragster guzzles nitro-methane.
 

Rich B.

Active member
253
41
28
Minot, ME
Buick Ownership
2016 LaCrosse & 2013 Boss 302 Mustang
Not sure on sluggish running either as you know all high octane does is keep engine from retarding timing, engine pinging and dieseling when shutting off engine. It's not more explosive, potent or anything as such.

High test is all I can use in my Boss Mustang with the TracKey or serious detonation can occur with engine firing on compression and not by plug. That's only reason, with normal key- regular gas is OK, 87 octane in ME and 91 for hi-test. See if I can find something. What Does Octane Do In Gasoline? Octane Ratings
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35
7
8
Buick Ownership
2011 Buick Lacrosse
Still am just had an early jump on them. just haven't seen nothing that I want to work with in a while. And right now hunting season is around the corner.
 
35
7
8
Buick Ownership
2011 Buick Lacrosse
Not sure on sluggish running either as you know all high octane does is keep engine from retarding timing, engine pinging and dieseling when shutting off engine. It's not more explosive, potent or anything as such.

High test is all I can use in my Boss Mustang with the TracKey or serious detonation can occur with engine firing on compression and not by plug. That's only reason, with normal key- regular gas is OK, 87 octane in ME and 91 for hi-test. See if I can find something. What Does Octane Do In Gasoline? Octane Ratings
Nice articel
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Rich B.

Active member
253
41
28
Minot, ME
Buick Ownership
2016 LaCrosse & 2013 Boss 302 Mustang
Roger that too on the Fall activities. Look forward to the hibernation months as things slow down a bit, take a break.

Not bragging or anything but only attempting to retain active posts and keep interesting. Have had many semi-fast cars since childhood. Let me think:
1) '67 Mustang fastback (Ford)
2) '69 road runner (Plymouth)
3) '79 'Lil Red Express Truck (with the chrome stack exhaust)
4) '84 Dodge Daytona Turbo Z
5) '87 Corvette (Chevy- put away in Winter)
6) '13 Boss Mustang (back to Mustang)

It's been fun but many I had to use as a daily driver. Put current car away each winter. Always wanted a car I didn't need to use. The Buick doesn't go out in storms but do use that through the cold months.

Love how these get so side tracked sometimes🤔
 

Radiator

Full Member
46
0
6
Oviedo, FL
Buick Ownership
2010 Buick Lacrosse CXS
Are you saying that you had this problem more than once. Is it the brand, OEM, MFG issue? When you have them replaced did you ever get a chance to take a look to see the damage? That does not sound good at all. I winder if that guy on youtube stuff actually worked with the gallon of whatever it is in the gas tank. I can go for it.
Unfortunately, I don't have any other information. One service advisor told me that there were a "batch of bad cats GM had that found their way onto some vehicles". I don't generally believe any of those guys given there BS about the octane of the fuel I was using being a possible culprit. For what it is worth, I have not had anymore cat problems after the 2 of them were replaced.
 
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