As a preventative measure, I am going to replace my oxygen sensors (83,000 miles on the factory set). The motor is an 01 SOHC V6 4.0. Any advice on which brand to use? They seem to be about $40 a piece! I haven't really gotten into it, but I'm assuming that I need 4 of them. Any help is appreciated!

 

FWIW, my 4.0L OHV came from the factory with Bosch 02 sensors and that's what I replaced them with.

 

Is this a maintenance item?....I don't see it in the owners manual maintenance schedule. Is there some gains expected that would justify the expense? Correct me but if an O2 sensor goes out wouldn't you get a CEL and the DTC would identify it, which you would service promptly when convenient....but your truck would not come to a stop on the highway. Don't get me worng, I am all for PM. Pat

 

One of mine threw a code at about 130K, so I replaced both (upstream) sensors.

 

Just replace the upstream O2 sensors, the downstream sensors only need to be replaced if they trow a code. Yes, O2 sensors are a maintenance item. The justifiable reasons for replacing them include increased fuel economy, increased performance, and not having to replace a several hundred dollar catalytic converter. I know its not in the owners manuals, but thats because the O2 sensors last more than 80,000 miles, which is beyond any warranty period, so the manufacturer doesn't care at that point. They would rather you buy a new vehicle.

 

Don't rplace them if they don't need it. You can clean them with a propane torch
though and it can save untold amounts of money if more folks did it. hold the sensor
in the flame for about 20 seconds and wipe it off, repeat until it untill there is no build
up carbon blocking the windows. Ususallly they fail because the exhaust stream can't
get to the wire inside. You can test the output voltage with a multimeter to see if
you are getting a proper signal!! Most of the time they get replaced and generally get
a bad rap since mechanics will replace them if you come in with driveability issues
when really the problem is the ratio is out of spec since the build up on the sensor
will not let it read the actual temp and can send the wrong amount of fuel which ends
up with more unburnt fuel getting deposited on the tip. You can also make your motor
run artificially too lean to clean it but removing it and doing it by hand is better.
Do not use any liquid cleaner on it I have heard of others using denatured alcohol
to make it cleaner but it doesn't need to be shiny to work, Just be sure the windows
are open so it can get the exhaust stream to it and it will work like NEW!!
If your motor has a Intake temp sensor you should clean it at the same time as well
as the Mass air flow sensor using the maf sensor cleaner to ensure you get a good
reading of your a/f ratio. If you had the ranger problem of a dirty MAF then cleaning
your O2 sensor is probably in order too since a rich burn makes it dirty and throws off
the reading.

 

Interesting. That is the first time I've ever heard of a way to clean an O2 sensor. Every post I've ever come across simply said replace it. Them little buggars aren't cheap in a big city, let alone out in the boonies where I live. A $50.00 part in Detroit will run me $75.00 UP here.

 

Do a search and the explanation on how to test them usually also tells you to
clean them with the propane torch before testing them with the torch.
YOu are basically looking for the voltage that gets created by the heat, Since
it is a ium metal they are really quite tough and lasts along time unless of course
the windows get clogged up or the wire itself get's gunked up. It is a thing that
bothers me to no end when I hear folks going to a mechanic and a car that doesn't
have a CEl that is running rough the mechanic swaps out the O2 sensor and of
course charges a premium on it plus the labor minimum for a job that takes 20 min
When cleaning the thing would do the exact same thing!! It is a great marketing
ploy to have popular opinion/MYTH be that it can't be cleaned and has to be replaced.
I think I forgot to put in the above post to be sure to apply some silver antisieze
to the threads to prevent it from sticking And DO NOT put any dielectric on the wire
end since the way they operate is by a temperature differntial from the hot side to
the cold side and if you block the air vent holes it won 't work. Which brings me to
another problem with them being on the bottom of the vehicle, If mud or tar gets
trappped and blocks the vent it won't work since it needs a supply of fresh air!! A
simple rag wipe down can get a Cel for an O2 turned off if that is the case and is
worth a look.

 

I have advocated on deaf ears for years, not to arbitrarily replace O2 sensors unless they test bad/lazy when bench tested and scoped.

It makes sense for the DIYer to learn to diagnose and test properly.

On the other side of the coin, those that ship the vehicle in to a shop will pay almost the same in labour for testing and not get the benifit if a fresh sensor.

But then, I am probably preaching to the converted..... my rant....P

 

From "Ford Fuel Injection & Electronic Engine Control" by, Dr. Charles Probst.
"The newer the sensor, the more the voltage changes, swinging from as low a .1v to as much as .9v. As an oxygen sensor ages, the voltage changes get smaller and slower, the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, NEVER APPLY VOLTAGE, and NEVER MEASURE RESISTANCE OF THE SENSOR CIRCUIT. Only use an analog meter with high impedence to measure the voltage output."

Cleaning with a hot flame sometimes works, sometimes doesn't. It can be used as a temporary fix. It does not return the sensor to its original, new condition.

O'Reilly has Bosch for $37.83 in my area. jd

 

You must have stock in Bosch too!! haha

 

Consider:

Some people with 90K+ on their Ranger will drop $250 or so on a fancy air intake system that looks great but doesn't really do much of anything for performance or MPG. Other people with similar mileage might resist that temptation and instead decide to spend under a hundred bucks for a couple of new 02 sensors that will (in all likelyhood) improve performance and gas mileage, if not immediatly, then almost certainly over the long haul.

So, who's getting more bang for the buck here?

 

So the logic about replacing or cleaning the O2 sensors is not so much about preventative maintenance but instead about maintaining like new performance? That as a justification I can understand better, especially as you apply Jim's info from Dr. Probst.

 

1998 ford explorer does anyone know where the 02 senser is bank 2

 

Bank 1= passenger side (#1 Cylinder)
Bank 2= driver side
sensor #1= closest to engine (upstream of CAT)
sensor #2= after/downstream of CAT

hope that makes sense....

So if you are looking for bank 2,#1 O2, , it would be the sensor closest to the engine on the passenger side.

Bank 2,#2 O2, is non existent if you have a Y exhaust with only one CAT...P