How do I change the O2 oxygen sensor on a 2003 Chevy Malibu?

Question

The Check Engine light is on on my Malibu and I'm guessing that it is the O2 sensor(s).
How tough is this to change and how do I get to it?
(The Malibu has 85,000 miles on it.)

Answer 1

Go to Autozone, they will let you use their OBDII reader. But be wary of any advice that they give you. As others have said your O2 sensors are probably not the cause. Get the codes that caused the Check Engine light to go on. Here is a list of all OBDII codes.

http://en.wikipedia.org/wiki/Table_of_OBD-II_Codes

Then Google the codes and your make/year of car and you will be amazed at how many people have had the same problem that you are experiencing. Just knowing the MIL codes doesn't automatically make this a no-brainer, it does make it 90% easier though.
If you get impatient and want to start replacing things do the cheap ones first like:
1. Look for a loose or cracked vacuum line. #1 cause of the MIL (Malfunction Indicator Light) going on.
2.Is your gas cap on tight and does it hold pressure?(yes that will cause MIL to go on)
3. a loose wire maybe? or a loose screw? (sorry i just had to-lol)

I speak from experience. My truck's MIL came on.
Autozone read codes :PO171 and PO174.
AZ guys says that's the downstream O2 sensors for sure. Replaced them, reset light, drove away happy -no light!
Two short trips later-MIL on! Crap can't pass CAL SMOG.
Took sensors back to AZ and got money back.
OK go to dealer- pay up the nose.
One last check...
PO171 and PO174 = lean bank 1 and 2.
lean = to much air to fuel. what's this?
....a leaky vacuum hose! I swear that I checked that at least 5 times.
Two or three short trips later the MIL goes off. Go to smog station for cert. As I start to tell the tech my story he blurts out,

"Oh yeah it's the little hose under the manifold, we see that all the time on F150's!"

Answer 2

There are 4. One on each exhaust manifold, one in front of the cat converter and one behind the cat converter. They are a silver tube shaped item with 4 wires coming out of it and they screw into the exhaust pipe. Takes a 7/8" wrench to remove them. I'd be careful just replacing the O2 sensors just because you have a O2 sensor code. A lot of the time a O2 sensor code is the symptom, not the cause. Good Luck! Just my opinion, I could be wrong.

Answer 3

O2 sensors are not hard to change, but they are expensive so I don't recommend simply guessing that it's the O2 sensors.

3 years is not a long time and O2 sensors typically last longer. I recommend getting the codes that triggered your check engine light before going after the sensors.

I also recommend doing engine tune up and changing things like the air filter before going after the O2 sensor.

However, if you still feel it's the O2 sensor. Just follow the exhaust manifold. There is usually one O2 sensor per exhaust manifold and one O2 sensor after the catalytic converter.

Get an O2 sensor socket or a box wrench to remove the sensor. They will be in there very tight and can be difficult to remove.

Answer 4

Try the mass air flow sensor first. O2 sensors do wear out but usually not that quick. If they are bad the code will be specific about it. Remember that if it's a pending code that activated the idiot light, you have to manually erase it to turn the light off.

Answer 5

first take it to autozone for a free scan. if it is the o2 sensor, ask them if its the one before or after the cat. if its before then take a 7/8'' open end wrench and you can get to it by reaching your hand down the back of the engine. i'm pretty sure its before the firewall on the exhaust pipe. once you get it out, unhook the wires, and then install the new one. tourge it down tight, but not hella tight. the o2 after the cat you have to crawl under the car. its the only sensor on the exhaust pipe under the car, and its right after the cat, in the middle of the car.

good luck.

Answer 6

if its a 5 speed then it wouldnt be the 02 sensor.. altho im a girl.... I know! lol. i had a truck and when i pushed the clutch in to downshift - the truck would shut off.. and that was bc of the 02 sensor.. i dont think that is the problem with ur car.. theres something else wrong with it.

Answer 7

it looks like a sparg plug, and it screws into the catalytic convertor right of the engine, youll need a stubby open in wrench prob 7/8 inch

Answer 8

there are too many sensors and just one light , try to get the code of the memory of the car and post it, i'll try to give some advice,

Answer 9

Ok I've finished taking off the one and putting the other on. How long will it take to get that light off .

Answer 10

you can look most of that stuff up on autozone's website. but your best bet i think would be to buy a Chiltons manual for your car. I think everyone should have one for the car that they own.