o2 sensor 4.6

does anyone know where to locate the O2 sensor on a 2000 GM with 4.6. This is the sensor the recomment to change about every 50k miles

There are 4 of them. Which one do you want??

There are 4 of them. Which one do you want?? I don't know of any O2 sensors that have a recommended replacement period. Most people want to change them cause it is an easy job that makes them money.

a friend of mine has this GM and we only get around 12mpg around town. she found on advance auto's website that sometimes the o2 sensors will cause poor gas mileage, and they recommend changing them about every 50k miles

http://www.partsamerica.com/MaintenanceOxygenSensors.aspx

a friend of mine has this GM and we only get around 12mpg around town. she found on advance auto's website that sometimes the o2 sensors will cause poor gas mileage, and they recommend changing them about every 50k miles

http://www.partsamerica.com/MaintenanceOxygenSensors.aspx

OK, Does your owners manual show a replacement interval - NO. Advance is in the part selling business.
#1 do not use the Bosch sensors sold by Advance. They do not work well in Ford Products. Always go OEM on anything emission or sensor related. With this engine only use Motorcraft plugs as well.
#2 - is the car throwing a check engine light? If so you need to start with the codes. Bad O2 sensors will almost always throw a code. Throwing O2 sensors based on a symptom would be a waste. There are 4 of them and they are about 115 bucks each from Ford. If the car is getting this bad of mileage and not throwing a code, you should start by paying the dealer for a one hour diagnosis. If it is an emissions problem, all smog stuff is warranteed under fed. law for 8yr./ 80k miles. My guess might be a converter problem or a tranny problem. My 95 has never gotten less than 19 around town and 26 on the road. Any teenagers in the house?? :)

Actually, the only time the FRONT HEGOs will "throw a code" is if they are completely inoperative, or the heaters quit. If they work, but are lazy for example, you will NOT get a code and your mileage WILL drop significantly. Your friend did NOT get what I would call "bad" advice. It might not fix anything, but what was suggested was reasonable, and I do see it a few times per year.

Actually, the only time the FRONT HEGOs will "throw a code" is if they are completely inoperative, or the heaters quit. If they work, but are lazy for example, you will NOT get a code and your mileage WILL drop significantly. Your friend did NOT get what I would call "bad" advice. It might not fix anything, but what was suggested was reasonable, and I do see it a few times per year.


I had my first O2 sensor failure at 140k a few weeks ago on my 95. (it is OBDll BTW) I can''t remember the code but it was for "Upstream O2 sensor Not enough switches" on my scan tool which also showed it as being lazy, not completely open. The point I was trying to make is that at $100 per just throwing sensors at it was an expensive way to go, especially with the fed. emissions warranty still in effect on the car. I believe the O2 sensors are covered under that. Much cheaper to pay for a one hour diagnostic at the dealer. If his car is running that rich that it is only getting barely above half the normal mileage it should be throwing a code somewhere. Get it properly diagnosed - generally much cheaper than pulling out the parts gun and firing at random! just my :2cents:

Just because you are getting that bad of gas mileage does not mean it is going to throw a code. The only time a computer will throw a code to turn the check engine light on is if the sensor it is monitoring is way out of the factory specs and it will throw a code if the senors it not working. Other than that the computer will throw codes but the problem is not bad enough to turn the light on.

i havent had a chance to look at the owners manual, again its not my car. No teenagers in the house, only two people drive it, my friend and i. I am the more aggressive of the two and when i drive, it averages around 17,

when she drives she averages 12-14 all around town. on a trip, we took, with AC running, we avg about 19. sounds like a problem to me but i dont know where to start. she is the one who found the info from advance.

i have an 89 towncar and around town i avg 17 and on the road, 20-21.

i want her to get rid of this thing.

just for giggles, check the fuel pressure. if the regultor is hung, it could cause too much fuel to go to the engine all the time and cause a rich running condition and could trip a code for the O2 sensor.

Just because you are getting that bad of gas mileage does not mean it is going to throw a code. The only time a computer will throw a code to turn the check engine light on is if the sensor it is monitoring is way out of the factory specs and it will throw a code if the senors it not working. Other than that the computer will throw codes but the problem is not bad enough to turn the light on.

It may not be throwing a code but it probably should be. OBDll has very little tolerance for rich mixtures. I still maintain that it would be cheaper in the long run to pay the 80 bucks for a diagnostic instead of throwing parts at it. If the car is running that poorly and isn't throwing a light, it may have pcm problems.
By the way, How many miles on the car? Mostly city or hwy?

going on 80k mostly city driving.

this is the most temperamental car ive had to deal with, other than my 72 lincoln.

also has trouble starting sometimes, it picks random times that you have to try and start it 2 3 or 4 times to get it running. its a 2000 model but it acts like its 30 years old.

could be i just dont like it.

going on 80k mostly city driving.

this is the most temperamental car ive had to deal with, other than my 72 lincoln.

also has trouble starting sometimes, it picks random times that you have to try and start it 2 3 or 4 times to get it running. its a 2000 model but it acts like its 30 years old.

could be i just dont like it.
Very surprising that you feel that way. I have had great service out of mine. At 80k city driving I would start with plugs and wires. Motorcraft only on both. Use dielectric grease in the boots. This will help rule out any base engine concerns. Maybe test the fuel pressure as Way2old said. A quick check on the fuel regulator is to pull the vacuum line off of it and check for gasoline in the line - even an odor of it. This would show a ruptured diaphram. Also may want to run some injector cleaner thru the tank, and others on these forums have shown performance improvements by cleaning the MAF sensor. Put a vacuum gage on the motor as well. Low idle vac (steady) can be a sign of a plugged converter. Beyond that, have a reputable dealer diagnose it. D & D motors in Greer used to have a good rep when I lived in your area. Are they still around?

yes D&D is still around. and doing well selling Fords because they are, for the most part, shot at 80k so they can sell a new one


I dont like her car because Ford has good ideas, but they have too much technology for their own good. They make their cars too expensive to maintain, so folks let them run down quick and just buy a new one.


im a Buick man. and not a pretend buick with a 3.1, a real Buick with a 3.8. I know people and I have had very good service from Buicks. No one i know has ever had any long time service from a Ford.
i have 2 lincolns myself, that were inherited, they are both very low mileage and have their share of problems. I have an 89 towncar that uses oil like crazy. and shouldnt with only 80k miles. other various and sundry ford problems over the years, too many to list.

in 3 buicks, ive replaced one intake manifold which was bad from the factory.

Has your friend maintained the car? Again, at 80 k it is probably due for some. Air filter, Fuel filter, and PCV all come to mind. Use only a Motorcraft on the PCV. Plugs and wires.... Get all the maintenance caught up to rule out base engine problems.
BTW, I just got rid of a 4 yr. old Pontiac with 98 k that was knocking like an SOB. GM ain't perfect by any means. And it was all highway miles.

i noticed on your posts you had the pontiac. if youre talking about the one you had its got what is known as a "chevy engine" the 3.1 is a shoddy engine. the 3.8 was actually developed by buick when they were their own division. its a much more reliable engine.

and easier to care for than the fords. its all just preference

i noticed on your posts you had the pontiac. if youre talking about the one you had its got what is known as a "chevy engine" the 3.1 is a shoddy engine. the 3.8 was actually developed by buick when they were their own division. its a much more reliable engine.

and easier to care for than the fords. its all just preference

The 3.1 used to be a great engine for reliability. Then they made changes to get better mileage and didn't test them completely.

As far as reliability, with the exception of the famous cracking intake in the late 90s models, the 4.6 Ford has been a paragon of reliability. Many taxi and limo fleets are running them over 500k miles without overhaul. I find mine ok to work on with the exception of the egr system crammed back against the firewall. I have never touched the EFI system, alternator, Water pump, or anything else attached to the engine. I have had the egr passages clog, and thats about it. Lower ball joints at 100k. one O2 sensor. The rest is brakes,tires, shocks, and other routine maintenance. The other things you may check are all your vacuum hoses. A vacuum leak will really make a car run poorly. The ones on the PCV line are prone to collapse and split - Murphys law says always on the bottom where you cant see it. :grinyes: