Mechanics

CHECK ENGINE LIGHT

2005 Buick La Crosse

Electrical problem
2005 Buick La Crosse 6 cyl Two Wheel Drive Automatic 43600 miles

The check engine light comes on with P0420 code. Regular system diagnostic test shows engine running clean. Freeze frame shows code being set only at idle, at 15 minutes and again at approximately 45 minutes. What is the cause and what is the fix?
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Buicklacrosse
September 1, 2010.



First of all thank you so much for your donation. Most of the time that code is caused by a bad catalytic convertor the good news is it is probably covered by your emission's warranty. What engine do you have the 3.6L or the 3.8L?Let me know so I can get you the correct information.

Saturntech9
Sep 1, 2010.
The car has the 3.8 engine. I forgot to include: Code #P0420 Catalyst System Low Efficiency Bank 1. Some one had suggested to me that an oxygen sensor could be the culprit since the mileage is only 43,600. The real mystery is it only triggers at idle. Thanks, Lou

Tiny
Buicklacrosse
Sep 1, 2010.


http://www.2carpros.com/forum/automotive_pictures/416332_2005_buick_la_crosse_code_P0420_part1_1.jpg



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http://www.2carpros.com/forum/automotive_pictures/416332_2005_buick_la_crosse_code_P0420_part13_1.jpg


There is the trouble tree for that code it's most likely the cat even with the low mileage i have seen cat's fail with even lower mileage then that.When your car idle's it has less exhaust going thru the cat and that mean's the cat has a colder temp so the code is more likely to set at idle.

Saturntech9
Sep 2, 2010.
Thank you for your prompt answers. I would like to leave positive feedback for you but it asks how many points to give and on the left side it says I have 2 points. Is that how many I am limited to giveyou? Also what is the best way to approach the GM dealer to avoid a " Lets try these parts first situation? Lou

Tiny
Buicklacrosse
Sep 2, 2010.
If you have 2 point's that's all you have to give someone you earn point's by someone giving them to you or by posting response's question's etc. What your going to have to do is go to the dealer and authorize a half hour to an hour diagnoses and if they find out it's the catalytic convertor or something else that is covered under your emission's warranty then buick will pay for the repair.I wouldn't let them play let's try this if the can't tell you it's going to fix the code P0420. But most of the time it's the cat for that code.

Saturntech9
Sep 2, 2010.