catalytic converter bad....again.

G-518172

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:
I have a 2012 LaCrosse and yesterday the same thing happened to the left side converter. They replaced the right one only a two months ago. Luckily, they were still under warranty.
 

Former GM employee

New member
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Buick Ownership
Don't own, trying to be helpful
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:
Your original bad o2 sensor led to the failed cat. It is most likely you have a leaking
fuel injector
that is causing your issues. You need to take is to a tech tlhat can perform a power balance test, and try to narrow down which injector/cylinder is the issue. I am a ASE Master Tech, and have seen this issue as described several times.
 

Former GM employee

New member
3
1
1
Buick Ownership
Don't own, trying to be helpful
Your original bad o2 sensor led to the failed cat. It is most likely you have a leaking
fuel injector
that is causing your issues. You need to take is to a tech tlhat can perform a power balance test, and try to narrow down which injector/cylinder is the issue. I am a ASE Master Tech, and have seen this issue as described several times.
I should have been more expansive in my reply. An intermittent miss from a marginal spark plug can also do this. Normally however, spark plug failure will cause the CEL light to come on with a P0300 dTC, plus a cylinder specific code (such as P0301, which would indicate a misfire in cylinder no. 1).
 

Radiator

Full Member
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Oviedo, FL
Buick Ownership
2010 Buick Lacrosse CXS
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....
By the way, to add to this...I have now made it about 60K miles since my last reported cat issue. I was doing some work to the car the other day and the crossover coolant line broke off in my hand. The coolant line runs from what I suspect is the thermostat to the coolant reservoir via a plastic quick disconnect that was brittle and broke off with very little effort.
 
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