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O2 Sensor locations?


Michael Nelson
08-07-2006, 09:57 PM
Hello all, I'm new (obviously).

I just bought a 2000 Crown Victoria Police Interceptor with 87k miles. Naturally it has some issues, most of which I've dealt with.

So the "Check Engine" light is on, the Ford service say I should replace the O2 Sensor (which one?).

They want to charge a huge amount, and I can't afford that right now.

So I was wondering where are the O2 Sensors located? Are they as easy to install as the Air Flow sensor? If they are easy to do myself I'll be saving like $400.

TIA for any help.

Johnny Mullet
08-07-2006, 10:09 PM
You gotta find out which )2 sensor is bad, and the code from the scanner would tell us. There are 4 02 sensors on that! It may not even be a sensor. You could have a PCV system leak or an intake leak.

Get a free scan and post the code here.

MT-2500
08-07-2006, 10:13 PM
Hello all, I'm new (obviously).

I just bought a 2000 Crown Victoria Police Interceptor with 87k miles. Naturally it has some issues, most of which I've dealt with.

So the "Check Engine" light is on, the Ford service say I should replace the O2 Sensor (which one?).

They want to charge a huge amount, and I can't afford that right now.

So I was wondering where are the O2 Sensors located? Are they as easy to install as the Air Flow sensor? If they are easy to do myself I'll be saving like $400.

TIA for any help.

Welcome on your first post on AF.

As just said we need that code no.
A check engine light or a 02 sensor code does not say replace the sensor.
It says check it out.
Many things can give you a 02 code.
What is the mileage and how is the tune up end?
What engine and what is the code no?
MT

Michael Nelson
08-07-2006, 10:19 PM
Thanks for the replies, the Ford Dealer service said I need an O2 Sensor. I only know of 2 for my car. I took it to AutoZone for a free scan and it came up something about the air and yes I forgot the code. They said it was generic and didn't know specifically what it meant.

If I can figure out where the sensors are located and if they are easy to replace I'm going to do that anyway. The car runs pretty good.

You asked for mileage, it has about 87k now.

MT-2500
08-07-2006, 10:34 PM
Thanks for the replies, the Ford Dealer service said I need an O2 Sensor. I only know of 2 for my car. I took it to AutoZone for a free scan and it came up something about the air and yes I forgot the code. They said it was generic and didn't know specifically what it meant.

If I can figure out where the sensors are located and if they are easy to replace I'm going to do that anyway. The car runs pretty good.

You asked for mileage, it has about 87k now.

Close to tune up time.
But if you want to throw away 500-750 $ in about 4 or 5 02 sensors go ahead.
It is your money.
Or post back code number and a little more info and someone will help you.

Michael Nelson
08-07-2006, 10:36 PM
Close to tune up time.
But if you want to throw away 500-750 $ in about 4 or 5 02 sensors go ahead.
It is your money.
Or post back code number and a little more info and someone will help you.
I'll go get it scanned again, but like I said it was an unspecific code.

Also just how many sensors does my car have? Because to order replacements anywhere it shows only 2.

I'm really asking where they are located and how difficult to change them. I know that these sensors should generally be changed anyway after about 60k miles.

BMW320i
08-08-2006, 03:03 AM
You need a special socket. Most stores carry them. It is a deep socket with a part of the side cut out for the wire to go. You need this if there is a clearance issue. You can also use a wrench if there is enough room. There are first always located on the exhaust pipe between the header and the rear muffler. Just get under it and feel around. You will see a wire sticking out and a small thumb sized metal thing attached to the wire and screwed into the exhaust. There is one before the CAT and one after the CAT. If you have true dual exhaust there will be four, two for each side. If you have sincle exhaust and one CAT then just 2. I have done two different cars O2 sensors. They are about $100 each. I always replace all the O2 sensors together.

MT-2500
08-08-2006, 08:57 AM
I'll go get it scanned again, but like I said it was an unspecific code.

Also just how many sensors does my car have? Because to order replacements anywhere it shows only 2.

I'm really asking where they are located and how difficult to change them. I know that these sensors should generally be changed anyway after about 60k miles.

The parts book may only show two different types/kinds BUT.
You may have up to 4-6 sensors on it.
No need to change them unless they are bad.
And sometimes when you get to fooling with them you may stir up more trouble. :grinyes: :rofl: :lol:


They are located from the exhaust manifiold all the way back to behind the cat.
Look around under there.
Some are easy to change and some are a bitch to change.
Do not replace them unless they are bad because Sometimes they outlast the car.
And a lot of times a 02 sensor code is caused by something else.
How is the tune up end on it?
A poor runing car in need of tune up stirs up a lot of 02 sensor codes.
Get the code and post back for help with it.
MT

Michael Nelson
08-08-2006, 09:01 AM
You need a special socket. Most stores carry them. It is a deep socket with a part of the side cut out for the wire to go. You need this if there is a clearance issue. You can also use a wrench if there is enough room. There are first always located on the exhaust pipe between the header and the rear muffler. Just get under it and feel around. You will see a wire sticking out and a small thumb sized metal thing attached to the wire and screwed into the exhaust. There is one before the CAT and one after the CAT. If you have true dual exhaust there will be four, two for each side. If you have sincle exhaust and one CAT then just 2. I have done two different cars O2 sensors. They are about $100 each. I always replace all the O2 sensors together.
Okay I see what you mean, with dual exhaust it would show that there are two but each one is doubled since 2 pipes. Well once I get the car up I'll look underneath thanks!

Depending on the wiring harness they will cost me about $42.99 each, so if I do all of them 171ish. Plus the tool whatever that costs.


The thing is, the car runs really well but that light is on. Yeah I'll get the code again though.

Hey, you know the flap on the gas filler that opens when you put in the nozzle? Well mine is stuck open like it's bent, maybe that could be the cause for the light? You know how they say don't fill your gas while the car is running or the Check light will come on? That's what made me think of it.


Thanks much!

BMW320i
08-08-2006, 09:34 AM
I have had several O2 snesors fail in my cars over the years. I have found that though it is always good to replace a part. O2 sensors are not hard to get by without. Thjey just fine tune the fuel ratio for optimal emissions. I have not had a car run bad with a O2 sensor out. I even installed 3 new ones on my Del Sol and the code never left. $40 aint bad for a O2 sensor.

Michael Nelson
08-08-2006, 09:39 AM
I have had several O2 snesors fail in my cars over the years. I have found that though it is always good to replace a part. O2 sensors are not hard to get by without. Thjey just fine tune the fuel ratio for optimal emissions. I have not had a car run bad with a O2 sensor out. I even installed 3 new ones on my Del Sol and the code never left. $40 aint bad for a O2 sensor.
Yeah it's not a bad price, plus it would be great if I could get the service dealer to pinpoint which one to fix (if I need to do just one).

Although I was thinking the light could be due to the gas filler hole flap like I said above. I wonder what that would cost to fix...

MT-2500
08-08-2006, 09:43 AM
Okay I see what you mean, with dual exhaust it would show that there are two but each one is doubled since 2 pipes. Well once I get the car up I'll look underneath thanks!

Depending on the wiring harness they will cost me about $42.99 each, so if I do all of them 171ish. Plus the tool whatever that costs.


The thing is, the car runs really well but that light is on. Yeah I'll get the code again though.

Hey, you know the flap on the gas filler that opens when you put in the nozzle? Well mine is stuck open like it's bent, maybe that could be the cause for the light? You know how they say don't fill your gas while the car is running or the Check light will come on? That's what made me think of it.


Thanks much!

Newer systems up to 3 sensors on the main side.
If your heart is all set on throwing parts at it replacing them with them cheap fit all sensors .
Go ahead and mess it up it is your car. Your money.
A good OEM sensor will run you 100-135$ . You do not get much for 42.95.
Good luck MT

BMW320i
08-08-2006, 09:45 AM
The flap is to keep large foriegn objects out of your tank. The cap can bring up a code if the cap fails. Worth a try buying another cap. You will have to have someone clear the code and see if it comes back. Most O2 sensor codes have a location. Don't pay the dealer to get your code. Go to a parts store and have them pull it for free. Sometimes they won't clear it for you though. Just inform them you are buying their cap and want the code cleared to see if it was that or if you need to buy more parts. ETC. If you are planning on buying only 1996 and newer cars it is worth it to buy a $100 code reader. I got one and love the hell out of it. DO all my friends cars too. Just get a OBD II code reader. Any generic one will do and they you can search the codes on the net.

BMW320i
08-08-2006, 09:49 AM
He is right if you do buy them buy the specific for your car not the ones you have to wire in. Besides it is a pain in the butt to do that anyways. My Honda I mentioned had to have a cheap ones at $100 each since honda wanted like $300 each. I never got rid of the code as I told you above. :banghead: At least get a good brand OEM replacement if the dealer cost is too high.

Michael Nelson
08-08-2006, 09:52 AM
The only sensors I saw were from $42.99 for OE to $60.00. Anyway like I said before I do anything at all I'm going to get it read again, and write down the code to post it.

I'll try to get them to clear it and use that reasoning only I'll buy some gas "treatment" and say that's what I'm using to fix it.

fleettech
08-08-2006, 10:31 PM
you do not need anything special to change them you can do it with I beleive a 7/8" wrench. I would be willing to bet none are bad and it is related to tune up,vacuum leak or a failing cat. you can get bosch o2 sensors at oreillys or get a motorcraft branded bosch at the dealer for alot more money. a bad gas cap will not cause an o2 sensor code that will show up as an evap. leak

krewl1
08-09-2006, 07:06 AM
Most of the time the O2 sensors that go bad on the vic are the downstream ones (the ones after the catalytic converter and before the muffler. Usually they are not to bad to get out . I would change both downstream O2 sensors since you are there and leave the front two O2 sensors in there until they foul up.

Michael Nelson
08-09-2006, 08:06 AM
It might not even be them, that's just what Ford told me I needed. I might get to AutoZone again have them read it, get the code. If so I'm going to try to ask them to reset it too.

raziullah007
08-09-2006, 01:27 PM
personally, on a car like this, i wouldn't even bother with that crap. I'm thinking about going with h pipe with exhaust cutout, thust turning it straight piple with the flip of a swith. O2 sensors really don't make that much of a difference. why don't you take the negative (or positive for that matter) off of the battery for 10 minutes, and then reconnect it. start the engine again. That should make the check engine light go away. (it resets the car's computer). I wouldn't bother replacing the sensor because they go bad very quickly anyway.

MT-2500
08-09-2006, 02:20 PM
personally, on a car like this, i wouldn't even bother with that crap. I'm thinking about going with h pipe with exhaust cutout, thust turning it straight piple with the flip of a swith. O2 sensors really don't make that much of a difference. why don't you take the negative (or positive for that matter) off of the battery for 10 minutes, and then reconnect it. start the engine again. That should make the check engine light go away. (it resets the car's computer). I wouldn't bother replacing the sensor because they go bad very quickly anyway.


Wake up to the modern repair world.
Anything over 1996 you have to have a scanner to clear codes.
And you need the 02 sensors working for proper fuel control.
Also jerking the positive battery cable can blow a couple of grand worth of PCM.
MT

Michael Nelson
08-09-2006, 05:25 PM
Had it checked again, it's P1131 which I guess is the O2 Sensors, but again which ones? The dealer said they didn't specifiy and didn't see it in the notes, but they offered to scan it again I said no thanks (not paying again).

So I'll probably replace the two downstream first and see if that does the trick. I'm going to have to pass emissions so I can't just leave it.

fleettech
08-09-2006, 05:45 PM
P0131 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)

it is an upstream (i beleive pass side)O2 sensor check the wiring and make sure it is not melted

MT-2500
08-09-2006, 05:59 PM
Had it checked again, it's P1131 which I guess is the O2 Sensors, but again which ones? The dealer said they didn't specifiy and didn't see it in the notes, but they offered to scan it again I said no thanks (not paying again).

So I'll probably replace the two downstream first and see if that does the trick. I'm going to have to pass emissions so I can't just leave it.


You are way off tract.
It is not a 02 sensor problem.
A code P1131 is system is to lean.
You have a lean running condition.
Check fuel pressure and maf sensor and for air/vacume leaks / tempt sensors or anything that would make it run lean.
Check fuel pressure and fuel filter first.
MT

ModMech
08-09-2006, 06:53 PM
According to this page, http://www.crownvic.net/ubbthreads/showflat.php?Cat=&Board=UBB23&Number=992473&page=0&view=collapsed&sb=5&o=&fpart=1 at a Crown Vic specific site (www.crownvic.net), the code P1131 is "Lack Of HO2S11 Switch - Sensor Indicates Lean".

It is VERY common for HO2 sensors to fail "lean", meaning no matter what, the signal they send indicates a lean condition, when there is not one.

If BOTH "front" sensors indicate lean, then it could be a vacuum leak.

HEGO (Heated Exhaust Gas Oxygen) sensors have an expected life of aproximately 100,000 miles in "normal" driving conditions, real-life is 50,000 to 150,000+ miles.

There are EXACTLY 4 "HEGOs" on the '96 to current "Panthers" (CV/GM/TC/MM).

The front TWO (one each side) are for fuel ratio feed-back to the PCM.

The rear TWO (one each side) tell the PCM if the front cats are functioning properly or have been tampered with/are worn out.

NO Panther has 5, or even 6 of these, and only the cars older than 1995 have only two. Furthermore, it does not matter wether you have single or dual exhaust, the number of HEGOs is EXACTLY the same in either case.

Members of the site report that NON-OE HEGO sensors DO NOT last as long, nor are they as accurate as the OE parts. Maybe you do not care.

It takes a SIGNIFICANT intake leak, or total loss of function on one injector to get the fuel ratio lean by 25% on one bank of a V8 engine - something you would CERTAINLY notice as a rough idle or part-throttle misfire.

Michael Nelson
08-09-2006, 07:06 PM
So are you basically saying I should replace all 4?

Even if I do this I'd have to do 2 at at time or something, plus where do I go that won't kill me in labor?

Johnny Mullet
08-09-2006, 07:46 PM
I told you there were 4 :nono:

Anyway, bank 1 sensor 1 is the O2 sensor closest to the engine on the passenger side. Try that first. Of course, you may have a vacuum leak or a PCV system leak causing the code.

Michael Nelson
08-09-2006, 11:10 PM
Okay so now all the conflicting things to do... why can't codes be more specific then?

I could replace all 4 sensors and the light could still come on with what some of you are saying. I don't know what to do here, I don't have alot of money. I paid enough for the car in the first place.... and thought I made a good deal.

So at least can we all agree that the O2 Sensors are the best to start with, and further the ones before the CAT? Or like has been said start with the passenger side one?

Edit: These ads that post with topics really are annoying. Especially considering I'm clicking the top ads everytime I visit. :(

MT-2500
08-10-2006, 08:30 AM
Okay so now all the conflicting things to do... why can't codes be more specific then?

I could replace all 4 sensors and the light could still come on with what some of you are saying. I don't know what to do here, I don't have alot of money. I paid enough for the car in the first place.... and thought I made a good deal.

So at least can we all agree that the O2 Sensors are the best to start with, and further the ones before the CAT? Or like has been said start with the passenger side one?

Edit: These ads that post with topics really are annoying. Especially considering I'm clicking the top ads everytime I visit. :(


It could go either way.:grinyes: :rofl: :lol:
If you just bought the car and the light was on or soon after is there not any warranty or a gaurantee or or they supossed to fix it to pass emmision inspection.?
Either way it needs some proper testing by a mechanic that knows what he is doing before throwing parts at it.
Codes do not always tell the story. They only point you in the direction.
Good Luck and let us know how it goes.
MT

Michael Nelson
08-10-2006, 09:40 AM
Well like I said Ford said they would do it, and the cost would be over $500. I don't have that kind of cash.

MT-2500
08-10-2006, 09:57 AM
Well like I said Ford said they would do it, and the cost would be over $500. I don't have that kind of cash.

Yes you said ford told you need a 02 sensor but did they run a proper diagnostic on it to find what sensor it was or check it out to find the real problem or just pull codes and want to throw parts at it?
If they charged you 90 dollars they should have checked it out good.
How about the people that sold it to you or is there any warranty or they supposed to fix it to pass emission inspection?
PROPER TESTING TO FIND THE PROBLEM WOULD BE THE BEST FIRST STEP.
Find a good repair shop that will check things out first.
Check around Ask around
Word of mouth.
Family friends coworkers neighbors business people and delivery people.
Mailmen and parcel delivery people get around and notice a lot of stuff.
Even a good parts house knows what shops are good and not good.
Chamber of commerce and better business bureau and city hall.
If you find a good referral to a repair shop go look them over and talk to them.
Look for a clean looking busy place with nice people running it.
Ask a few questions and ask about their qualifications and training.
Not all places have trained tech/mechanics.
If they do not find a place that does.
Even all dealers do not have all trained techs/mechanics.

Good Luck MT

Michael Nelson
08-10-2006, 10:03 AM
Okay thanks, I'll do that. I'll ask around at work about a repair shop that'll investigate it better.

Makes sense too, since what if I got all 4 O2 Sensors and it turned out to be something else or the light stayed on?

Thanks alot, too bad offhand I don't know of any repair shops.

Oh, I was thinking of getting a tune up, should I not bother with that?

MT-2500
08-10-2006, 10:40 AM
Okay thanks, I'll do that. I'll ask around at work about a repair shop that'll investigate it better.

Makes sense too, since what if I got all 4 O2 Sensors and it turned out to be something else or the light stayed on?

Thanks alot, too bad offhand I don't know of any repair shops.

Oh, I was thinking of getting a tune up, should I not bother with that?

Have them look it over when they check it out.
Needing a Tune up may even be part of the problem.
Good Luck
MT

Michael Nelson
08-15-2006, 01:26 PM
Update: Two hours ago had the code cleared, so far the check engine light has not returned :)

Also, just passed emissions!

Johnny Mullet
08-16-2006, 09:00 AM
Good deal!

Michael Nelson
08-16-2006, 01:09 PM
It just came back on, oh well back to square one.

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