I bought a used 2001 Century a few months ago. It needed some repairs so i got the fuel pump replaced; it was running rich so i changed the plugs and wires; got it aligned, changed a wheel hub assembly, rotated tires, etc. After over 1k of repair costs, i thought i was finally in the clear of all the problems. Not the engine is stalling, i smell exhaust outside of the car while running, and its throwing a lean code. Can someone help me get some idea of what it might be so i can procede with getting it fixed

 

What engine is in the car and what was the code #.

 

3.1 V6
Codes: P0134, P0171

 

MOST of the time when you get these two codes together it is the result of a poor/non functioning oxygen sensor. In this case it is for bank 1 which has cyls 1,3,&5. They are the front most cyls toward the radiator. Follow the exhaust manifold on this bank down to the O2 sensor in the exhaust pipe. Not a difficult job to replace with the correct tools. If you are goint to put anti-sieze compound on the replacement sensor , use it sparingly on the threads only . Once the repair is completed you must give the computer some time to adjust to the new working sensor. There are other ways to speed up the adapting process but they are not necessary if you have the time to drive it a little.

 

Thanks i really appreciate it. Should i not be running the car much since its running lean? And will replacing the sensor correct the ratio of gas to O2 so it will run properly?

 

I wish I could give you the answer you are seeking, but not being there the best I can offer is, most of the time this takes care of the code problem. Anytime a repair is completed that affects the computer's input info , you have the choice of disconnecting the battery so the computer will start from scratch or clearing the info retained with a scan tool . If you drive it a while the computer will adapt to the new info. Also, if you disconnect the battery you will lose all radio station memory and other accessory info in the computer(ECM).

 

Well, i ordered a new O2 sensor for pre-cat bank one. Replaced the sensor a little earlier today. Cleaned out the codes with a diagnostic comp, and about ten miles later, it threw out codes again. Went and pulled up the codes; still getting the lean code and bank 1 O2 code as well as a new code about a heating bank. Not sure what to do now lol (codes are now PO131, PO135 and PO171)

 

Was this the UNIVERSAL one or the one for our cars? some of the universal ones don't work. I can try to find the ones I used when I swapped both of mine over the summer. Have you also tried cleaning the MAF sensor and honeycomb with MAF cleaner aerosol?

 

No i havent tried that route yet. The O2 sensor i ordered was specifically for the Buick Century. I ordered it online through Car Parts Warehouse, and though you may cringe when i say that lol, i have ordered other parts through them and they have been pretty reliable thus far.

 

I ordered mine from advanced with my window switch, solid rubber motor mount, and something else. Don't remember if the front and rear looked the same with connectors. did them at different times.