My sister needs one of her oxygen sensors replaced. We know that they go on either side of the catalytic converter, but we don't know where the converter is. Does anyone know where the catalytic converter on a 2004 Chevy Impala 3.8L v6 would be?
Need help with something.
- Thread starter TestedAcorn
- Start date
bruceb
Diamond Member
- Aug 20, 2004
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Under the car, usually along the passenger side ... just follow the exhaust pipe
It is easily identified .. but you may need a special socket which has a slot in
the side for the wires, to remove the O2 sensor ... In some cases, depending on
the clearance, you can use a large box end wrench. And when you install the new
O2 sensor, be sure it has some Antiseize on the threads. It should come from the
supplier with that already on it.
It is easily identified .. but you may need a special socket which has a slot in
the side for the wires, to remove the O2 sensor ... In some cases, depending on
the clearance, you can use a large box end wrench. And when you install the new
O2 sensor, be sure it has some Antiseize on the threads. It should come from the
supplier with that already on it.
That's pretty helpful but what i really need is some kind of diagram of the engine and all of it's components (my dad's request). I've been looking on the internet for quite a long time, maybe at least 1/2 of the day.
bruceb
Diamond Member
- Aug 20, 2004
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Not to insult, but once you get under the car, it will be plain as day.
The O2 sensor sticks out about 1 1/2 inches from the exhaust pipe.
It mounts sideways to the pipe and has either anywhere from 1 to 3
wires, depending on if it is a heated sensor or not.
The O2 sensor sticks out about 1 1/2 inches from the exhaust pipe.
It mounts sideways to the pipe and has either anywhere from 1 to 3
wires, depending on if it is a heated sensor or not.
Bignate603
Lifer
- Sep 5, 2000
- 13,897
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Go spend the $10 and get a Haynes manual. They'll have it at an Autozone. It will have a diagram.
alkemyst
No Lifer
- Feb 13, 2001
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Yeah no offense...but if someone needs pictures and stuff for this type of job they may want to take it in. An O2 replacement is cheap as far as labor goes.
The most important thing is WHICH O2 needs replacing the upstream or downstream...if you don't know that, it's going to be a problem.
The most important thing is WHICH O2 needs replacing the upstream or downstream...if you don't know that, it's going to be a problem.
Gamingphreek
Lifer
- Mar 31, 2003
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If you need a Haynes manual to figure this out you shouldn't be changing it yourself in the first place. Do you know what type of O2 sensor you are buying (OEM or Generic Fit)? Do you know which sensor you are replacing? Who told you this needed replacing (ie: For what symptoms)
OP: Usually the exhaust pipe is on the opposite side of the car that the gas tank is on (For obvious reasons).
Coming from the engine, you will have the upstream O2 sensor (Wires and fitting) immediately before the Catalytic converter. After that you will see the downstream sensor (Looks exactly the same) and then the muffler.
-Kevin
Well I thought the same thing, but my dad said he wanted to know exactly what he was doing before he was going crawling under a car (My dad is 52 yrs old). I don't take offense or anything.
Gamingphreek
Lifer
- Mar 31, 2003
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That is completely understandable, but he shouldn't be going under this car in that case. Do you know the answers to any of my previous questions? I only ask because, if you guys aren't quite sure where the Cat is, then I wonder how you are so certain what needs replacing.
-Kevin
It's not the Cat that we need to replace, it's the o2 sensor located either in front of it or behind it.
Gamingphreek
Lifer
- Mar 31, 2003
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Well yes, but I was wondering how you know there is something wrong with the O2 sensor. There is no O2 sensor code you can pull from an OBD-II reader-- did you bring it to a mechanic or something?
Edit: I'm not trying to insult you guys or anything, I just would hate for you guys to go through all of this and not be 100% positive it is the O2 sensor (And by all of this, there isn't that much involved in changing the sensor assuming OEM Fit)
JasonSix78
Platinum Member
- Mar 5, 2005
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Ripped from Autozone's website:
Pre-Cat Sensor Location
Post-Cat Sensor Location
Here's the link the diagrams are ripped from: Text
It's possible there are two o2 sensors since it's a V6, one on each exhaust manifold (see pre-cat location above). This can be confirmed in a few seconds just by looking but I'm 99.9% sure it will.
Downstream/Upstream locations is a no-brainer. o2 sensor(s) before the cat, o2 sensor(s) after the cat. Cat location can be found just by finding these two sets of o2 sensors.
Pre-Cat Sensor Location
Post-Cat Sensor Location
Here's the link the diagrams are ripped from: Text
It's possible there are two o2 sensors since it's a V6, one on each exhaust manifold (see pre-cat location above). This can be confirmed in a few seconds just by looking but I'm 99.9% sure it will.
Downstream/Upstream locations is a no-brainer. o2 sensor(s) before the cat, o2 sensor(s) after the cat. Cat location can be found just by finding these two sets of o2 sensors.
JasonSix78
Platinum Member
- Mar 5, 2005
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If he's directly underneath the post-cat sensor location he'll still be able to see it. The shield covering the o2 sensor wiring will have a space in between it and the exhaust system for movement.
Gamingphreek
Lifer
- Mar 31, 2003
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My gas tank is on the drivers side, my exhaust pipe is on the passengers side. Unless you have dual exhaust (Doesn't matter whether it is from Single or Dual manifold) then it is kept on the opposite side of the car. In the event of a crash or a gas leak, it doesn't drip (and ultimately ignite) on the very hot exhaust.
-Kevin
There are several o2 sensor specific obd2 codes that will pinpoint which sensor. Most v engines will have two upstream o2 sensors by the way. Usually they both go bad at about the same rate so I would recommend replacing them both in any case. Also, the upstream (before cat) o2 sensor is almost always the one to go. It lives a harder life and unfortunately is far more important for the engine than the downstream o2 sensor (downstream sensors are used to check the cat efficiency).
Since your car has a transverse mounted v6, one of the sensors will be behind the engine by the firewall probably. You might have to get under the car to see it.
Since your car has a transverse mounted v6, one of the sensors will be behind the engine by the firewall probably. You might have to get under the car to see it.
Gamingphreek
Lifer
- Mar 31, 2003
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