Question about Buick Century

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1994 Buick Century 3.1L went from 20 m.p.g. to 10 m.p.g. I have replaced wires,plugs and oxygen sensor. I have taken e.g.r. off and reb up car (no smoke) Car runs and starts well :with sluggist slow speed pick up some time

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  • Anonymous Oct 14, 2008

    Changed the plugs, and now its running rough with small backfires. Slow to accelerate. Being the back side plugs were difficult to change, not 100% sure there in the right order.

  • Anonymous May 09, 2009

    Changing the back plugs on the my car was a pain, but the number one problem of doing this to a Buick Century is putting the back plugs in sideways abit and it makes everything eles fail. Well thats what I did and been told my a few local shops around me. Same problem.

  • Anonymous Mar 30, 2014

    After the sensor was replaced we hit bump in the road and the tranny and speedometer started working. Later it went back to not working again. I was told there were two different priced sensor for this car, what is the diff in them?



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Speed sensor. It plugs in to the transmission you can see it right in front. Just pulls out. You can find one pretty easy on the net for around 40 bucks. Unplugging a working one gives same results, slow pickup speed low mpg.

Posted on Jul 02, 2009

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Check the fuel pressure first, then have the exhaust back pressure checked, your Catalytic converter may be staring to plug.

Posted on Jul 28, 2008


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Rayder, 1994 Buick Century WIRING DIAGRAM. Check the attached links,instruction and guides, Good luck
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Aug 27, 2016 | 1994 Buick Century

1 Answer

Fast idle 1994 buick century

If it only started after the hoses were replaced, it suggests an air leak was introduced during the work.

Nov 08, 2013 | 1994 Buick Century

1 Answer

2003 buick century where is the oxygen sensor

Hello guys, this picture may be able to help you. oxygen sensor

Aug 21, 2012 | 1993 Buick Century

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1994 buick century brakes went out fluid leaking from rear

Brake lines by rear door on drivers side are a common failure point. lines under door failing can cause a total brake failure. Just replace and bleed the lines.

May 31, 2012 | 1994 Buick Century

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1998 buick century code p0420

code p 0420 refers to cat converter system bank 1---efficiency below threshold====causes ---cat converter---wiring---HO2S (heated oxygen sensor, the one in the exhaust manifold before the cat converter)
code p 0300 is random misfires
I would suggest changing the HO2S as it reports to the ECM on exhaust content so that the ECM can adjust the air/fuel ratio
so it is logical that if that unit is not reporting correctly, the cat converter may be having trouble burning off the gasses correctly
The oxygen sensor(O2S) reads the results of the cat converter operation and helps fine tune the ECM settings

Mar 10, 2017 | 1998 Buick Century

1 Answer

Were is the oxygen sensor (front) on a 2003 buick century

follow the exhaust pipe frontwards from the tail pipe. when you get about half way you will encounter a screw-in plug thing with wires coming from it, which is the downstream O2 sensor, then a big bulbous thing which is the converter, then another screw-in plug thing with wires which is the upstream O2 (front) sensor. Or if you can find the exhaust manifold, which will be quite hot for a while after driving, and follow the exhaust pipe backwards you encounter the same critter. If you do not have a lift or a good jack then most likely will not be an easy task.

Sep 20, 2010 | 2003 Buick Century

1 Answer

How to replace an oxygen sensor on a 1994 buick lesabre

you have 2 bank one or 2? either one you need a special tool to remove sensor location on exhaust under car under drivers seat unplug sensor apply tool turn counter clock wise until it comes out,make sure you plug new sensor in upon installation

Aug 14, 2010 | 1994 Buick LeSabre

1 Answer

Ok we changed the ignition module in our 1987 buick century, 2.5 liter and now when you start the car it just dies continuiously but once we get it started it will go but acts like it wants to die at stop...

Did you replace the crank sensor that is bolted to the back of the module? Is it possible that you got two of the plug wires switched. Or maybe 1 of the two coils is bad.

Apr 23, 2010 | 1987 Buick Century

1 Answer

Where is the oxygen sensor

It's on the rear exhaust manifold. You will need a oxygen sensor socket to remove it. If you are not saving it & tend to replace it, snip wires & use a normal socket. Saves the price of the special socket! Good luck!

Oct 10, 2009 | 1993 Buick Century

1 Answer

1994 Buick Century [four cylinder engine]

You might have your computer checked to make sure the circuit that controls egr valve is working.  On my vehicle, I had several egr valves changed and failed the emissions test until I had the computer changed and the PROMS updated with the latest PROM.
The EGR valve is easy to change because it is on top of the engine.  It has electrical coils that control the valve and one of the valves may be damaged where it can not compensate at idle.  If the EGR is working, when the engine first starts the engine should increase in idle speed and then switch to a lower idle speed.  This is part of the EGR system check and it adjusts as the engine increases in temperature.
There are several other reasons if one of the Emission sensors is faulty that may cause the rough idle.  The oxygen sensor, tempearture sensor, MAP sensor,...etc.  You may have a trusted mechanic attempt to read any codes on the engine.

Aug 12, 2008 | 1994 Buick Century

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